71 parts car 74 swinger project?

Yes, all of the stuff mechanically and sheet metal from the doors forward will bolt on.
Honestly, i would build the car that is more rust free out of the two, regardless of having the '74 media blasted already.
BTW, the '71 will have small bolt pattern drum brakes on the front which in my opinion are junk.
At least go with the big bolt pattern front discs on the front with the modern steering components etc. Parts are a lot cheaper and plentiful for this as well as a lot better.
How about pics of both cars?
Just my 2 cents........
Tom.