I know that a number of the tube crossmember suppliers provide an option for either 5.0 or 4.6 into Fox chassis. Ford moved the engine fwd an inch when they went to the SN95s where you could move the eng back atleast an inch in the fox so I would look at moving it as far back as possible. I would think your worse case would be finding a 94/95 crossmember or tube crossmember. I would think seriously about using a 351W instead of a 302 for reliability, they are less likely to split down the middle at stock hp. For space if a 4 cam 4.6 will fit a 302/351/460 will fit.
