Just to complicate things a bit, there used to be a domestic OO (Double-Oh) scale at 1:72.  It rose in the late '30's and was popular through the '40's.  Lionel made a line of OO models that were very nice for the period. The track gauge was 0.75", and the wheel and flangeway standards were the same as for HO.  Some enterprising early O scale modelers noted that the track gauge was three feet in O scale, and began using OO mechanisms, wheels, trucks and track to build On3 models.  If you look at an NMRA standards gauge for On3, it is actually labeled OO/On3. 

I'm pretty sure that first Shay pic on page 12 is printed backwards.  IIRC, there were only a couple of "left-handed" Shays, and they were two-cylinders, narrow gauge, and built for export.  I would note that at one time Ford Motor Co. had a Shay for a plant switcher.  Henry Ford didn't like the off-center boiler design, so they had Lima build one with the boiler centered on the frame. 

My first HO loco was an Athearn Hi-F PRR F-7, bought at a Washington's Birthday sale (remember those?) in about 1958.  I set aside trains for a few years, then got back into HO - bought a Mantua Pacific kit, followed by Athearn's "Little Monster" and USRA 0-6-0.  Then came a brass Olympia Ma and Pa 4-6-0.  All are long gone, having moved to On3 in the early 1970's.

The engine by itself is probably good for 7 or 8 percent.  I would stick to around 4 percent in order to pull a decent train. 

I was going to guess the Land-O-Lakes reefer might be an old Mantua kit from the late '40's/early '50's.

1965 sounds about right.  There was an ad in RMC for a summer sale special.  The sale also featured the Reading I-5 Camelback and one other loco I can't recall any more.

My first HO loco was a PRR Hi-F F-7, bought at a Washington's Birthday sale when I was maybe 12.  I really didn't get seriously into scale trains until late high school.  I helped my grandfather build a garage one summer and that got me enough to buy a Mantua Pacific kit.  Still hate all those valve gear rivets.  Then came a sale on some brass Gem models and I got a Ma and Pa Ten-wheeler for $29.50. 

BTW, the prototype of No. 7 is well on its way to restoration for full operation, maybe as soon as this year.  The brass model was done by both Gem and Akane.  The Akane version generally ran much better than the Gems.  As for the old-time Ma and Pa 2-8-0, PFM imported lots of them in the '60's.  I haven't tried to price one recently but they probably can be had for what a new Bachmann model would cost. 

On this page, the first two are photos of the assemblage in England of the preserved Gresley A-4 Pacifics.  Mallard holds the "official" steam speed record of 126 mph.  IIRC, this assemblage commerated that feat.  The next pic looks to be a Welsh narrow gauge train.  The trolley is operated at the Lowell, Mass.  textile factory museum.  The steam loco is stuffed and mounted.  The loco No. 40 belongs to the New Hope and Ivyland RR at New Hope, PA, running in regular tourist service.  Shay No. 4 is on the Cass Scenic RR in Cass, WV.  The sidelined loco is unfamiliar.  The 2-10-0 is obviously European, and may be Russian.  The next pic is a British railfan trip.  The set of GG-1's are parked in Philadelphia.  In all likelyhood they are laying over during the Army-Navy football game before heading out with passenger extras when the game is over.  My guess is that the photo is probably late '50's/early '60's.

The locomotive was ultimately sold to the Age of Steam Roundhouse museum in Sugar Creek, OH.  It's likely going to be a parts donor for sister No. 1293 which is operable.  There were 3 in the cab - two firemen and the engineer who owned the loco and ran the railroad.  The two firemen were injured but recovered.  The engineer was badly scalded and almost died.  He did eventually recover to some extent but passed away a few years later mostly as a result of the injuries from the accident.  I was working on the train and saw it all. 

This is the proximate reason why there are no more train rides in Gettysburg:  https://www.ntsb.gov/safety/safety-studies/Documents/SIR9605.pdf

I know that someone once imported brass models of the curved-side cars.  Best to keep an eye out on e-bay.  I note that the trolley museum in Washington, PA has just put one of the real cars back in service.

If you read the report on the Gettysburg incident closely, the proximate cause was almost total blockage of one of the valves feeding the glass, which did allow some water to show in the glass, but it was not an accurate indication.  The engineer had needed to blow down the glass before operating the engine to assess the flow through the glass.  Because there was some water showing in the glass, the fireman believed he did not need to pump more water into the boiler. 

Motive power was a couple of Class A Climax locos.  Climax engines seemed to be popula down under.  Be cool if Mr. Bachmann would make a Class A (hint, hint!)

Cass No. 12 was built by Lima as a three-truck Shay.  The shop forces at Cass rebuilt the engine to a four-trucker.  I presume they got the extra truck from Lima, but built the new tank themselves.