Congrats!
I too am sort of a purist with the Vega.
But, it is more of a dare to be different.
A SBC swap is sooooo.... overdone.
Keep the SOHC, but put performance parts on it.
Or swap in a DOHC V-6 from a mid-90's Monte Carlo ( turning it longitudinally to power the rear wheels, of course ) and put a 5-speed from a S-10 truck in it. No pussy automatic.
There are so many V-8 Vegas out there already and a many for sale. Lot's of choices.
A rust-free 'survivor' is rare even if this one has been painted and the interior re-done.
But, hey, you are a Vega owner now, do what you want. Again, congrats!