[TheSilverBuick]

I used a spare NAPA stock Buick 455 starter motor. I had a timing problem last spring on one of my 455's and cracked two nose cones, but the shafts appeared to still be straight and were collecting dust in the corner of my shop. So I bought an OHC nose cone off Jeff (Hamlin?) and installed it on the Buick starter motor. The motor itself is a hair larger than the stock OHC one, less than 1/4" bigger in overall diameter, so the opposite of what you are going for.

I don't know how any of the aftermarket small hi-torque starters will work. Some of them have a crap ton of adjustments on mounting block though. Considering some don't run any nose cone at all, a regular aftermarket GM issue one might work just fine on the OHC. Just do like you should for any aftermarket starter and check the tooth interference and have it shimmed accordingly so it doesn't grind or eat stuff.

You can see it's a big bastard in this picture.