If I were running the V8 I would run the truck bell housing with the mounts for the crossmember and what ever mounts you want to run on the front. you may have a bit of clearance problems with the heads/valve covers at the firewall though. You will also have clearance problems between the left manifold and the steering box.
The old and crude fix was to slide the steering box out to the outside and inch and a half using a piece of angle iron. As I said crude. It also ended up putting the steering wheel at a slight angle.
I prefer not to hack the center crossmember out as that will eventually allow the cab to settle when the weight of the cab on the mount brackets twist the top of the cab rails out allowing the cab to sag. One reason that you see a lot of these AD trucks that look slightly bent in the middle and the hood/fenders and cab don't line up very well. They will settle until the bottom of the cab rides on the frame rails but the damage is done.
