When running it with the throttle firewalled, don't you introduce a
real risk of overspeed? Will the engine really make it to TBO running
at max RPMs (especially considering the effects of ram-air and whatnot
at speed)?

What is "overspeed" on a fixed prop?

"Max RPMs" on an O-320 (and, in fact, all aircraft engines) are so retarded
that the engine is really just loping along at 2700 rpm.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"