Gears

Been running 3:55's with 350/700r4 combo in my trucks for years and that ratio keeps it in the power band yet allows the o.d. to work correctly at 70! tires are 235 60 r 15's.

 

There are lots of ways to get that much power....but yeah, if you're relying on sky high rpm, then you need some gear

 

I changed from a 3.55 open rear to a 3.23 sure grip in my 56 dodge pickup...the truck still has great punch off the line, and highway cruising is effortless...I'm using a mild 318 and torque flite 727 automatic....perfect combination!!!

 

Jim, I know you get all this, but I'll elaborate. As the power/wieght ratio goes down, for a given amount of rpm, the gear ratio goes up(taller). Heavier car, more gear, lighter car taller gear. More power (at a given rpm) taller gear. Motor for motor, you will make more power at roughly the same rpm artificially aspirated(nitrous/supercharger/turbo) than you will naturally aspirated, so again, taller gear.
Taller gears also have a negative effect on the amount of cylinder pressure/compression ratio the engine will tolerate on a given amount of octane.