Gears & Axles - Th400, what gears for the rear?

So im switching from my six speed which i've had forever to a th400.

Never had anything but my six speed, and never had a 3 speed in my life.

The car is in six. LSX 454 with a 300 shot. I'm expecting to be somewhere in the high 140 to 150ish trap i'd assume and I dont wanna run out of gear.

I know the 4.11s in the 12 bolt right now wont do...

is there some kind of calculator, or does someone know the gear to mph ratio? Planning on either a 26 or 28" tire and I'll be reving to 7400rpm.

any help, or a point in the right direction would help! thanks!

3.70 gears with a 28" tall tire should be just right for you. Bob

Think I can make mid-low 130s on motor with 4.11s?

Think I can make mid-low 130s on motor with 4.11s?

If that engine is put together with all the right parts, it should. Bob

If that engine is put together with all the right parts, it should. Bob

I ment without running out of gear :D

If its capable of 130 on motor, will a th400 with 4.11s make it across the line before I hit 7400 rpm on a 26" or 28" tire? :-D

there's gotta be some kind of standard.. do people just guess and check or what?? fbody.org is no help anymore :(

Think I can make mid-low 130s on motor with 4.11s?

Man it will be close... i have 4.10, 28's, an d th-400 at 6900 i was top out at 126 and i ran a lil out of gear shortly after the 1/8 on spray... so i am going to a 3.73 i believe just my .02cents