I donot believe there is a 9,000RPM motor made that does not require a lot of maintance, look at the prostock guys, they check valve train every round and changing springs between rounds is common practice and they are running on 1.888 rod bearing and 3.25 stroke with 2.300 main bearings and i'll guarentee you those engines come down between races and everything is magnafluxed for cracks. Nascar engines run 500 miles but low compression and also small bearings and fully rollerized and tese motors cost well over $40,000.00 each. I don't think you can build one that will live like a bracket motor and not have to spend lots of money and lots of maintance. In another post i said i knew a guy who had a 288" Nickens and Brown motor that ran all season comming out of the hole at 10,500RPM and he did not break all season, but the car slowed down from 8.80's to 9.20's after about 50 passes.
JMO
Zip.