Not as common as before, but you may be able to find a '78-'85 Chevy Caprice, Monte Carlo, or Camaro in a salvage yard...Most of those came with factory A/C, and most, if not all engine related components would fit your Avanti.
There was another Stude Avanti/Pontiac swap done as a shop project at a trade school here in Mass around 1970....
A really nice install of a 389 Pontiac GTO engine into a '63 Studebaker Avanti...The Pontiac was equipped with the popular three two barrel carbs...I only saw that Avanti once, and really liked it!
Some taller folks have found the Studebaker Avanti driver's seat adjustment range a bit limited, and have cured this by extending the ends of the seat tracks to get the seat to go further back.
That's too bad....Very typical of how many Studebaker owners treated their front suspension parts back in the day when these cars were in regular service....A few shots of grease for the front suspension parts, on a regular basis, would have made the Stude/Avanti front end suspension almost bullet proof.
Relocating battery to trunk gets all that 3EE weight off the front end fiberglass...Conversion is quite easy, and the obsolete 3EE can be gutted and left in stock location for appearance sake.
A bit unusual...
Your upper & lower control arm bushings are all in good shape..could there have been earlier accident damage on this Avanti?... Bent suspension part?