4 OR 5 speed

[COPO427]

If you go with the offset shifter and the Tremec then you won't need to butcher the floor. See http://www.classicchevy5speed.com/

If the Tremec is anything like the 5-spd Richmond, then you may want to go with the 6 speed as 5th gear is darn close to reverse since it's back and not to the front as the 4-spd.

The M22 is sweet noise to your ears, here's mine with 4.10 in my 70 Z28 www.nastyz28.com/~copo/m22sounds.zip
The M22 will be a slouch with 3.55's off the line. The M20 would be the best combo with the 3.55's. I'd go with the M22 wide ratio with the 3.55's. The ratio of the M22W is close to the M20 so if you like the noise in the 1,2 gears mostly then go with it.