I use a relatively stock one behind my 505.

I rebuilt it using better clutches, removed the governor, used a FWD pattern mvb and put the amount of springs in the front drum that Turbo action recommended. Other than that, it is pretty much stock.

It gets regular beatings on the track and street but I never do a 1st gear burnout, either!

Make sure you use a bronze thrust washer as most kits come with the fiber one and mine likes to eat those!