Steve, very sorry to hear about the crack in the block (saw your post on WayOT). I'd just go forward with the spare engine and have the crack looked at for repair. I'd be surprised if it were in an area that couldn't be fixed. Of course, your parts would be worth more in pieces.

Couple thoughts: the flywheel shouldn't give you any issues with fast RPM drop. As you know, the B5 guys have been running LWFWs for a decade now without issue. The engine management is a bit more sophisticated than the '91 911 system.

If you eliminate the secondary air injection pump, I'd buy yours. Mine is making quite a bit of bearing noise.

General comment: this forum is spoiled! Lifts are a rare commodity. Though Steve is indeed "the man" for doing this job on jackstands, it's not a rare thing in the true DIY community. Having a lift is the rare thing. I've pulled countless S4 engines on jackstands both with subframe drop methods and lift out. I pulled and rebuilt my Esprit engine all on jackstands in a cramped space. It can be done.