You can use a lot of Mustang SVO, Lincoln and Ranger front end parts, also the old standby, Mustang ll, Granada and Fairmonts.You'll want a rack and pinion too. I would recommend a subframe connector and rally bar for the engine bay.
or you could go with all old stuff from a v8 car, but I would recommend disc brakes.You can use a old parts catalog to see what is v8. Just about everything was upgraded between the 6 and 8
some will tell you it can't be done, but I have seen it done. It's just a real tight fit between the water pump and radiator.
I've been planing on building one myself and have most everything.
Here are two of my groups, let us know your progress
that Mustang Monthly project 6 to 8 is pretty good and here are the complete stories including the Front suspension,
from our group links: