That was my thought exactly.
If you do want to build a V8 Vega make sure that the car hasn't been hacked on. It's easier to start from scratch than fix someone else's mess.
Read the links that I posted the search for above especially the Don Hardy one. He is pretty well recognized as the guru of the V8 Vega set.
There should be cars of that body style around with a dead or dying 4 banger for a couple hundred bucks or less in most areas. They may take a bit of hunting but since they made over 2 million of them there are some out there.
One of my autoshop students had one (the one that cracked windshields) that ran in the 12s with a mild 350 and was a terror on the street until his little brother took out an apple tree with it.