Just go and buy a NP205 which you can pick up for cheap. Then call up advanced adapters and get there adapter for the conversion. I have no idea how much its worth but they are probably the only ones that can help you.
The NV 4500 will mate to the 85-91 NP 205 case. Must be 32 spline. According to the AA Catalog, some minor mods may be needed for linkage,and/or depending on shaft length, a new spacer. Of course you could just scrap the whole idea, and let me take that old NV 4500 off your hands!