The volare is one of the more common IFS swaps on the old fords. (Welded in however!) There are about 12-13 IFS that I know about. The mustang II suspension is one of the best, but also one of the most expensive out there now. Just a basic non-PS "kit" (wheel to wheel) is around $1500 and they go up fast from there.

A volare IFS is as cheap as you can find a donor car. I am waiting on mine for a while. I want to drive it with some minor straight axle mods and see how it does. I think the aerostar IFS would probably be my choice if I go IFS. Very little or no frame cutting at all involved.