My first choice here would be a Mustang II kit, however to do a complete installation with big GM disks and a power rack you'll probably spend about a grand. (Just did one on my '53).

Since you have the two Novas at your disposal I would suggest going with the 78 rather than the 80. (Just personal preference there.) Do not use a Camaro because they're a bit too wide. Some people will also recommend a '70s Chevy truck suspension which is almost a direct bolt on but that is a bit too wide as well and just doesn't look right.

I believe you've been given really good advice here. Make sure you measure twice and be very careful lining everything up before you weld. Also make sure whoever does your welding is certified. You're life and others will depend on the quality of these welds so don't skimp. Always think safety, safety, safety.

Just my opinion, but if you do all the welding and work yourself and you take the time to rebuild the Nova's front end (bushings, springs, ball joints, rotors, calipers, bearings, steering etc.) you'll probably spend almost as much as a basic Mustang II kit would have cost. Definitely if you have to pay someone else for the welding.

One other thing to consider is the difficulty of remounting all the stock sheet metal on a new/different front frame. This can be time consuming to say the least. Sometimes it pays to spend a little more money up front to save yourself a lot of work later.

Good luck whichever way you go.