CumminsFever
I'm Awesome
My brother had a 73 nova that originally had a 307. It wiped a cam at less than 100k miles. Machine shop warned us about the cam issues as we hunted for another engine. So yes, the cams can be an issue.If it is a '77 check the cam lobes really well. Late 70 to early 80's were known to have soft cams.
It isn't "all" of them though. Just ones from a certain plant... that I of course can't remember! This is if I am recalling my details correctly.
I wouldn't have a problem using the old engine with vortec stuff clamped on top of it. It will get you down the road for a while, and maybe for a very long time!
I've personally taken a 77 350 and clamped tbi heads/intake onto it, just to prove it can be done. No problems with tbi.
Vortec may be different, but I bet it'd work too. You'll need to follow the advice regarding timing cover and flywheel.