Cristiano
Ask for more definition on the crank. I thought all the 385 series cranks accepted a standard pilot bearing like Napa part BRG B66067. This is what I use with my 514/TKO. 1.8525OD .695ID
I also agree that a 5 speed is really not necessary, but if you go with 4 gears, make sure you have a high enough rear gear to keep you under 2500 rpms in 4th at 70mph or it will drive you crazy.
My Superformance has a 3.73 rear gear and TKO with .68OD which works OK for me... !st is nice in heavy traffic, but useless otherwise.. I launch in 2nd at the drag strip just because 1st is so low.
Hear is a handy application when playing around with gear ratios
http://www.secondstrike.com/Technical/GearCalc.asp
Craig