engine/trans build

[fizz]

In talking to 2 well known reputable mopar engine builders, with my target of a 12 second(flat for conversation purposes) well mannered power tour type car, 550 + hp approx. 500 cu in, six pack, auto trans, both are its a no big deal build. Both know I can spend what it takes. One is a flat tappet cam, minimul porting on eddy heads guy, other is ported eddy heads roller cam guy. The flat tappet cam guy avoids the expense of lifter bore alignment and bushing, bronze timing gear, expensive lifters. Roller cam guy(hydraulic) says to check the bores, but don't worry about bushing unless something is really wrong. Both think an overdrive trans(gear vendors) is kind of a waste for my build, run 3.23 gears. I do need to be able to run extended 75 mph to be satisfied. Opinions?