My 8.97:1 493 does 500hp 600 ft/lbs with RPM heads and an MP509 on 87 regular.

For what you want to do I would put more cylinder head on my shortblock and as much hyd cam as I could put in it and still live with a 25-2800 converter. Something around 114 LSA with .600ish lift.

This should make for a nice no maintenance mid 5000 to low 6000 rpm combo that can go coast to coast for 100,000 plus miles and do it on reg gas for the most part.

Mine makes over 500 ft/lbs from 2000 on with the MP509 and it was quite happy to pull the stock converter but the power brakes and EFI didn't care for the less than 10" of vac and the 1100 rpm idle was banging the crap out of the driveline. I put in a 2800 advertised TA converter and now it's easier on the driveline but harder on the tires.

And then there is always the boost option. Cake and eat it too.

Kevin