Paul, The IN/Out box you have will work with the V860. 28dryer is correct. Most of the V860 Got the back of the block cut os about 2 or 3 inch. We used to cut the block in a large band saw and then face it square to the crankshaft in the mill. After that was done we would drill and tap 6 bolts in the lip of the block to attach it to a ¼ thick motor plate. The top two block bolts usually needed to have a piece welded in to get enough material to drill and tap. Once the plate was bolted to the shortened block the In/out box would bolt to the plate. The crankshaft drive that you have needs to be made to the correct length to engage the shift coupler allowing slight end play when in gear. Then the main shaft of the Box needs to be machined to fit your pilot bushing and cut to length. This entire fitment needs to be done with the block shortened. Crank/ motor plate and in/out box installed. I believe that you could do the same work to the shaft and coupler without shortening the block. My only concerns would be the Long coupler hanging of the back of the Crankshaft and the overall length of the engine /In/out box. I have attached a couple of photos to give a idea of how much we cut off the blocks.