I love the old Fords. My last pickup was a '66 F-100, 240 straight 6, 3 on the tree. 286,000miles on it when I installed a new long block. I miss that old dependable behemoth. It got roughly the same 12mpg loaded, or unloaded. Did a lot of work with that truck.
Your's is looking good.
I had a '68 like that. The 240 was the same as the 300 except for the stroke. Most of the parts other than the rods and the block were interchangeable. It was very reliable but didn't have quite the torque of the 300.
The guy I bought it from had a good 4 spd in his shop so I took it home with that in it for an extra $100 (this was in the late 70's).
I moved to California with everything I owned packed in and on a '68 ford mustang. (Looked like something out of Mad Max, with spare tires and jerry cans chained on top of the trunk.) Five years later, it was a '66 F-100 headed back the other way..
Shifter tubes are a problem on the column shifter. I went through 5 junk yard replacements, (none worked) before swapping to a floor shifter.
That 240 straight 6 had enough room under the hood, that I stood along side the engine, under the hood in a pouring rain, changing spark plugs, without gwtting wet! (Try that with anything modern).
And yes, the 300 had a longer stroke, and the 250 was a bored out 240. (Only 3 engines would fit without modifications. )
First gear would just about climb trees, but 3rd gear didn't like hills much.