If memory serves me... the first year of the nv4500 for gm used a different bolt pattern than the later gm and dodge versions. It may very well bolt up to a 235 bellhousing. I am pretty sure that the bellhousing will have to be bored in the middle as the bearing retainer would be much wider than that of a sm420.
I am doing this swap in my 1940 gmc. I elected to use the dodge version from 94-97. The dodge version has a 1 inch longer input shaft which makes it a very ez conversion with an adapter plate. I needed to use the stock bellhousing because the brake and clutch pedals mount to that.
Another thing to consider is the speedometer hookup. Gm versions of this transmission used a velocity sensor (electronic) and would have to be converted to work with stock guages. the 94-97 dodge versions have a speedo driven gear which could be used for a mechanical speedo.
I think the Nv4500 is an excellent choice in our stovebolts if you are going to do some heavier hauling, or plan to build that 235 for more power. You have a truck, why not use it like one.
Good Luck!
John
