How many using an A500 overdrive ?

Yeah I know about the hydraulic vs electronic units. The A100 will require me to make a lower cross member. And I know that the driveshaft will be short/ but I think that there is room to make it work.
Anyone have any problems with breakage ? I will probably never have make than 300HP.
I like the fact that the A500 has a lower 1st gear/ weighs less/ and robs less power from the driveline/ and is about 1" shorter in length than the A518.
I would prefer a lockup unit (whats the best vehicle to get on from & years for the hydraulic unit 42rh with lockup?)
How tall of tire are you guys running ? I've got 225/70/15 27.4" Dia .
Sounds like a win-win to me.