used 283's in donor cars are kinda rare these days. Others can verify, but the 283 hasn't been put in new cars since early or mid 60's. Whereas a 350 can be had up until NOW, in one form or another. I would think you could find a 350 powered donor car (or truck) cheap, lots cheaper than a 283 one, especailly up in Maine!

Remember, what is cheapest? what is most common and most available! (probably the 305, but spend the extra $50 and get a 350)

As to other chassis items - YES! get the brakes, etc up to spec first. an old car as yours is has lots of wear and just plain age on it. ALL teh rubber suspension bushings are no doubt shot. You should be able to get a kit for $200 or less and intalling it will keep you busy for awhile (long enough peraps you can save up more money) and learn more from us here.

Somtimes you can find motors in the stangest places...440 Chrysler and 727, 45,000 miles for $750. Includes free 21' motor home. SO keep an open mind and be PATIENT!