So the 88.5 inch belt should work? I'll give that one a try first then.
No, but I have read about the interference with the battery tray. I did a trunk mount battery in my blue car (a '73 Swinger with a 318) and it worked out very well. No slow cranking issues or anything like that. I bought a rather expensive AGM battery for it, and now I'm planning on selling that car in the spring, so I think I'll put that one back to stock configuration and use those parts to do the rear mount battery in the car that will be getting the Magnum. *Edit* ...which is also a '73 Swinger, albeit one that was a slant from the factory.
But before any of that happens, I'm going to be putting it on the run stand I built. I've never rebuilt an engine before so I'd like to verify operation, oil pressure, no leaks, etc. before actually putting it into the car.