thing i have a clue about is the engines. if the 500 engine is a single cam and the 420 is a single cam engine i think you will find that they are pretty much the same dimensions. the 500 engine out of an sl may have different manifolds since that chassis is different from the e class.

good luck on an interesting project.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.