Scale-o-rama idea: a 1/100 F-15 has about the same length and wingspan as a 1/72 F-16.
Take a Revell 1/100 easykit F-15 for the basic airframe and graft on suitable 1/72 parts from an F-16 or F/A-18.
Maybe in the promo livery of the early Vipers?
One or two engines? There were all sorts of interesting proposals (some more wild than others) for what would later be the "Teen Series".
Add an arrestor hook and a launch bar for a carrier-borne variant? Export carrier-borne multi-role fighter? Not as capable as Tomcats and Hornets, but more modern than Crusaders and Skyhawks and able to use smaller carriers, (such as those of France, the UK or Australia)?