I've got the same Commercial Craftsman 12-36 as you just sold. Its been my 'spare' lathe for many years. I got mine new in the box but around 11 years old at the time. A local company had bought several of them and put a few in storage. I have the original invoice for mine, sold in 1975, it came with the original manual, crate, and even a Sears Commercial Tool catalog for that year.
My uncle gave $100 for it through a buddy of his that worked for that company. they were re-allocating the storage space where that and few other machines were being stored for future use. They offered the equipment to employees for cheap.
I put it together for the first time in the late 80's.
It don't see a lot of use but comes in handy.
As far as getting used to a new machine, its not as bad as it may first seem. you'll be surprised how fast you pick up on how to run a new machine.
The only machine I ever ran that was really confusing was an imported offbrand 16-60 variable speed 3 phase lathe they bought at work.
The biggest issue was that the thing could be reversed both mechanically and electrically. You had to really pay attention to what you were doing when running that one. It didn't stick around for long, the boss himself crashed it pretty bad one day and did a ton of damage, after fixing it it got sold and replaced with a more conventional Clausing unit.