This would not be that bad of a project. You can get those aftermarket universal clutch pedal, make a mount for it beside the auto. brake pedal, bolt a master to the firewall, and run a hydraulic line to the slave.
And the shifter would not be set back at all, it will come out thru the base end of the dog house, you will need to cut the floor abit if it's a C6 van, if E4OD van, you'll be fine. The E4OD vans have a longer base at the dog house for the much bigger transmission compared to the C6, witch was shorter.
Here is a '79 E100 with an NP435 4spd, works fine with the "shorter" C6 style dog house (this is a factory NP435 van though).
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And here is a 1990 E150 conversion van, factory M5OD, the ZF5 shifter would be at the exact same location on an E4OD style "longer" doghouse.
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Heres the universal clutch pedal I was talking about
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Oh, I knew I had this picture somewhere, heres a 4x4 ZF5 installed, behind a 6BT cummins in an 86 Ford van.
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