If ya wanna cobble......check out those Ricumbili thereads we were mulling over
a few weeks back. They are Cuban kids homebuilts where they swipe generator motors off Soviet tanks down there and make some the most ....well ya just gotta see them. But they will be right down your alley.
Deacon was kicking around a way of mounting a sprocket to the front wheel
and mounting a string trimmer or chain saw above the front wheel. Since your chain saw has a centrifigul clutch already a few simple adaptations could have you riding high. I'd figure the exhaust would be your larest secondary issue after you're up and running. (you may want to run a tube down one fork and put a muffler on it there so the noise and smoke are vented away from you.
I'd love to see photos of your old Studie Pickup. I've seen some old Studie's at auto shows where they had cars, pickup's and a dump truck. When I was a kid I used to work for this guy who had a grocery store and he would pick me up on saturday mornings in his old 60 (some model) Studie pick up. It looked alot different than the earlier ones.