I've never been sorry I put an IO-240B in my airplane, and with regard to
what it spins at most of the time? I typically fly along at 2200 rpm's, and if
I want to go VNE & faster I firewall it and let it wrap up to 2700-2800. Low
power gets me 120'ish, and depending on weather and weight I get 1'000
to 2'000 fpm climb.

I can also throttle it down to 1500, and lumber along burning no fuel, and
it's happy going slow.

I've seen several auto conversions, and while I've seen some nice machine
work every once has been undergoing constant maintenance. Or working
on solutions to "problems" which seems the bane of their existance.

The Corvair motors seem nice, but I spent too many days reading the KR
guys postings about broken cranks, etc. That seems a risky business to
me.

If I built another one, Rotax, Lycoming, and Continental would be the only
motors I'd be looking at.

Jeff