TH400 VS. T56 6 SPEED? Faster? Better?

[MGONCHAR]

Hello, I am new to the site. I am reading alot about Auto's Vs. Manuals. Obviously an automatic is a quicker more efficent shift, if you are comparing the equall amount of gears. However if you compare 3 gears in an automatic to a 5-6 speed manual, is an automatic really quicker? with the right gearing, isn't a 6 speed like having a 3 speed transmission with in between gears like a 2 1/2, 2 3/4 and an extra 3 1/2 gear? would this not keep you in you horsepower range more efficently? I know a TH400 has an equall 1st gear, however second is like a 1.7 to 1 wherein the 6 speed is like 2.2. In the same car wouldn't the 6 speed run a better 1/4 mile and have better top end?

The reason I am so interested is because I am considering putting a 6spd trans in my 67 camaro with a TH400 w/3500 stall. The cost is between $2500-3500. I would hate to spend all this money if it is not going to make a significant difference. Any feedback is appretiated