To me, it all depends on the car, the seller and how I judge all of that. If the thing is buried in the snow/cold, he may NOT want you screwing with it . . . sometimes Old Timers have THEIR reasons for waiting until Spring (like he doesn't want to be outside having to supervise this crap). The fact that it is outside, kind of tells me it is probably not a pristine all-original 32 roadster in top shape . . . so maybe I don't need to be in a big ole' hurry about it.
If everything seems on the up and up, then just draw up a simple 'contract' that states the following:
1) What you are buying -- Make, model, year, vin number, etc.
2) Exact description of everything that "comes with the deal" -- if there are parts in sheds, then write it all down . . . just capture everything you're buying. If there is anything that doesn't come with the deal - call it out.
3) Description of the condition (if that matters).
4) That the stated person (name, address, phone, etc). is the legal owner of the vehicle and has the right to sell it.
5) Total purchase price and all "conditions" of the deal:
a) How much of a deposit - and how the 'balance' will be handled. (Cash, certified check, etc).
b) By what date you have to pick it up
c) What happens if you don't make it by that date (does he keep the deposit and tell you to pound sand?)
d) That he or somebody he designates will provide access to the vehicle, parts, buildings, etc - for you to pick it up at a later date.
e) That upon pickup, you will have a valid pink-slip, title, etc. - conveyed to release interest in the vehicle.
f) Dates and signatures of both parties. I'd then go to a place to photo-copy the original document (such that he has a copy as well). Or - bring two copies and sign/date both.
I've done this type of stuff multiple times. If you plan on going this route, then you need to have a clear conversation with the seller - to see if he agrees to these terms/conditions BEFORE you take a trip. Some folks won't sign anything - strictly cash and carry.
Good luck - keep us posted.
B&S