OK, just to clarify which setup is this?
This one? Lots have guy's have run Mustang 2 setups in those trucks with the six cylinder with no problem. My 53 1/2 ton had a manual rack M2 (Car not kit) setup in it with the 216 when I got it. Later I swapped to a later 58 car motor with no problem. When it goes all back together this next round it will get a power rack and pump so the wife can drive it more. You should have more clearance with a kit M2 than with a regular Car cross member?
Just to clarify till you can post some pics. Is this the original engine in that truck? How bout posting the engine #'s so we can look it up and work out just what engine or more important what oil pan we're looking at. Also what trans are you going to run and have there been any other mods to the truck before this.
If you need you can email those pics to me I'll be happy to host them and post a link for you.
Remember "Ain't No Crime Runnin' Inline!!!"
MONGO