check the junkyards man, i just brought home a good running and totally complete 1983 carb caprice 305 engine tonight(minus the alternator) for 200 bones out of a yard in springfield to put into the t/a for a while just to get it back on the road again, i took it through the car wash as soon as i got back into town and its all clean now and looking good
car-part.com is where i found it
its just a 305 but its complete and runs good and is a direct fit into the t/a in which was originally 305 anyways and the car will run and drive just fine with it, well worth the 200 bones, and a warranty to boot
good luck
