Mygrain,
Not all Indy motors are useless. It depends on the vintage. The early Indy motors used Off center blocks which will work for our application. Indy Light motors have a lot of good stuff in them that we can use and are 274" to boot.
The short deck Indy blocks are very unique. To the best of my knowledge they used 2.66" strokes and thus the deck was very short. Just looking at one I would say the difference is greater than .500".
The lifter bores in the block were re-located for the square port heads they ran and require special cams, lifters etc. The blocks are dry sump too which isn't a huge deal. They are completely incompatible with anything on a GN.
Check out the one over on Ebay and you'll see what I mean about the lifter bores etc. Weird stuff.
Neal