1967 Valiant Suspension Dilema

Just my $.02, it all depends on what you want to do. There are plenty of companies that you can buy individual suspension components for and if you do your research can can get a well balanced vehicle for A) Handling around curves/canyon carving/around town or B) Gripping hard in a straight line for drag racing
Just a couple of easy companies to look at is PST (they are vendors here and offer discounts for FABO members). Or look into the Hotchkis TVS system if you have the $$. Both retain stock style suspension, just updated for more modern performance
In my head, and some will disagree with me, the general rule of thumb is if you want to drag race, then go big block. If you want to corner hard, then go small block. But I know people have been successful using small blocks in drag racing, and big blocks in handling applications, its just harder to accomplish. (The biggest issue is the weight involved)
You have a lot to look into but you have a great head start, good luck on your build!