Thanks for the input. Hyde, I'll be in touch!
Here are a few pictures. The silver car is a J4. It has the same roof height and the body lines. It has a 98 inch wheelbase. The J5 has the same low roof line and body lines. It has slanted dual headlights instead of the J4's single headlight. The J5 had a 102-108 inch wheelbase. The longer the wheelbase the less I like it.
The side profile is of an X300GT. It had a 3 inch taller roof, an oval snout, and a 96 inch wheelbase.
The blue roadster is a J6 that had the roof cut off. The J6's hood doesn't slant down as much and the radiator opening is larger.
The drawing is of a J4/5 with an oval grill.
The stock C4 suspension results in a 71 inch width. The Body width of the Kellison is 67 inches. So, I have to widen the body, or flare the wheel arches, or build a custom frame and narrow the C4 suspension.
When I look at the pictures my favorite car is the J4. I like the single headlights, and shorter wheelbase. I'm thinking of keeping the roof, shortening the body to fit the C4 wheelbase, modest fender flares so that I can use the C4 chassis, and changing the radiator opening from rectangle to more paper clip oval. This weekend I plan to strip the C4 and see how the body fits.