[elhigh]

The Duke used the same bellhousing pattern as the 60-degree V6. Bolts right up.

If you're serious about this I don't recommend the Duke. I love them irrationally, they aren't powerful or sophisticated (and sophistication is overrated) but they are dogged and relentless. They're like the SBC of largish fours, right up there with the Toyota 22R in terms of longevity.

But along the same lines is the Mercury Marine 3.0. Back in the day Pontiac also produced the Super Duty Four, a racing-bred 4-banger that could be bored out to over 200 cubic inches and reliably crank out 300 horsepower. It was Duke architecture but with heavier internals to handle the stresses. The Mercury block is supplied by GM and is a halfway step between the Duke and the SD4. It'll pump out over 130 hp - much better than any Duke - all day long. If you were of a mind to upgrade to a higher output, there's room there without endangering the engine's lifespan. Boat motors are built rugged.

For the chassis I'd screw the Merc into a Celebrity wagon. I always thought those had the best proportions of any GM wagon, ever. 135 is approximately equal to the "high performance"* Eurosport VR models, and a 5-speed manual was available behind the V6 option, so there are 60-degree compatible manuals to be had. It's within the realm of possibility.

You'd have better luck installing a newer four-pot, however. Tuning and efficiency are such that you'd probably get more power and more mileage, and still may have a shot at bolting on the 5-speed. For my part I really like the idea of the old-school boat motor and a period Getrag tranny in a Celebrity, but that's me. You do you.

* When talking about Chevy Celebrities, "high performance" has to be in quotes.