will an OD unit take it

I have one behind a hot 360 (around 370 HP) and it is taking the abuse of burn outs and hard launches just fine (so far 5k miles and 30k prior to that behind a hot \6).

The issue with the alumium case is the shaft the counter shaft rides on over time can elongate the holes in the case and allow the gears to seperate. If that becomes excessive BOOM. There is a fix which envolves drilling out the case and pressing in a steel bushing for the shaft. With this fix the tranny is as strong as any A833.

Mine has not had the modification.

As far as the gear spacing is concerned the 360 has enough torque that the gear spacing is not an issue for a street car, I am running 3.55 gears. Even with the \6 it was not an issue for 1-2 or 2-3, the 3-4 shift was like most vehicles with an overdrive top gear, big rpm drop.

Certainly the OD tranny is not ideal for the drag strip but on a street car it is sure nice to be able to run down the highway at 60 and be turning less than 2k rpm's.