Why stop at OBA, when you can have a OBW as well.
I dont have pics yet but here is what I have done.
go to pick n pull, look at the ford cars, not sure what year but a newer one, say 90's.
Lots of these cars used the york ac unit, most were mounted sideways on the passanger side of the engine, (cut the hoses as far back as you can). under the york, bolted to its side is a bracket that holds a large, in my case 100A altinater. You may be able to use all of the brackets from one car. In my case, I found a bracket for a york on a ford truck that would bolt right up to the head on my 289. This bracket had holes for the bottom of the york.
So what I ended up with is: A bracket from a ford truck ~'70s f150 bolted to my 289 head, the york bolted to it sitting upright on the drivers side, the altinater and bracket bolted to the right side of the york.
Parts from PnP were < $100
If your interested I'll try to get some pics