EXACTLY. Fix what you have first. You're gonna be awful disappointed if you replace the engine and it turns out that there is a problem with the fuel line collapsing or some similar problem. After you getting it running properly and tuned up, I would work on the brakes and suspension. They are 46 years old and were barely adequate when it was new. I'd look at replacing the rubber bushings, ball joints, shocks and maybe even the torsion bars and rear leafs. Make the car solid and safe before you start putting more power to it.
