I am thinking of the Chevy LS series engines, but my admittedly hair-brained idea would be the same for others. My concern is that even with dry-sump oiling the starter ring gear limits how low the engine can be mounted.
If a flex plate from a completely different engine could be mated to a button flywheel made for my engine, then I could end up with a smaller diameter assembly. I have made my own starter motor mounts before, but not for moving it toward the center of a smaller diameter. The major restraint on that would be clearance between the starter and the engine. Or, it could be mounted at the top of the bell housing facing back over the transmission like an old Bugatti. Of course, the starter would have to be strong enough to turn a V8, so that would eliminate a lot of flywheel/starter combinations.
I did say it was a bit hair-brained didn't I?
Keith