About to buy an early '86 - questions before buying

[crshbandit]

I just bought this 86 Supra, only thinking it had a minor oil leak and a rough idle. Took it to a friend, ( who is a former toyota mechanic) , and he said 3 of the six cylinders are only at about 50 PSI compression. SUCKS! I was hoping to only put about a grand into this car and have something unique and fun to drive for the summer. Now I have been calling around for remanufactured motors, and the cheapest I could find was $4000.00!! YIKES! The car has 157000 mi. on it but it is clean inside and out, except for some rust on the rocker panels and some spots on the sunroof. I was planning on fixing the rust myself and doing the brakes, but 4Gs for a rebuilt?? I did find a used motor with 70000 miles on it that will come with a 6 month 6000 mile warranty, for $1750.00. I really don't know what to do at this point. Not sure if I want to put that kind of money into a car this old. What do you guys think?? Thanks for any help.