This has been posted before but here it is again.
A simple adapter can be made at home with NO machine tools.
This will get you from an A/B block to a Chev V8 bell housing which will then get you to many different transmissions with no more mods other tham mounts.
The adapter needs a 2 inch thick by 9 by 10 inch piece of aluminum and a 1/4 inch thick piece of aluminum 18 inches square. Everything behind the block becomes Chev and that means cheap. Lots of used stuff besides you can get new at any parts house across the country.
You use a Chev flywheel and clutch etc, bell housing and starter etc. Starter moves to the right side where there is more room.