Very similar mechanically, completely different electronically.     Then there are two 'P38 4.0' versions the earlier box plenum + Lucas GEMS are different from later banana-bunch plenum + Bosch Motronic.
As for the gas, who knows?  You might have to be more specific.  If it's a single-point mixer style system, you'd probably be disappointed - they fight with the more sophisticated engine management on the later cars.
cheers, Ross K