A 235 is about 3.8 liters isn't it? Did GM ever put a TBI on a Buick 3.8? That might provide some appropriately sized parts.
Have you looked into one of the two barrel or four barrel manifolds for the 235?
Since one of the problems with a single carb on an inline six is the difference in mixture between the center and outer cylinders, I'm suddenly wondering if you can tune the injector trigger to squirt more for the front and rear cylinders...
My thoughts about fuel injection usually center around putting a TPI on a big block. I've never gotten very far considering it for a Stovebolt.
