is there a drive that will work without redoing transom?

which drive??? and what do you have for power???

302 ford eaton 2 on a 1970 donzi

So its a eaton II drive and you want to updat the boat with a newer style drive..with you having a ford engine you dont have alot of choices..volvo and volvo are the current ones that have ford bellhousings for your ford engine..unless you wanted to update the whole thing and put a chevy combo in the boat..

will Volvo fit in same hole in transom as the eaton ll or will transom have to be filled and recut

is yours the one that does a 180* swing for trailering? is so then you may be able to get away with a volvo housing because they are big..but if it were me i woulf gomercruiser and convert to chevy..