Like a lot of builders, once the dead boxes started piling up from kit bashes, I set a rule that using the parts I needed would not create an orphan kit. Either another version could be built, or, with some swapping from other kits, the donor could still get finished.

Soooo... for the engine, there are several donors common at swap tables and dusty shelves. Any of the '66-69 Galaxies will have the SOHC parts, as will the '68 Shelby GT-500. The '69 has the injection system, too, so keep that in mind as well.

Snagging the cammer parts out of those will still leave you with an easily buildable kit, even though the age of the tooling might be a challenge.

Also, there were a lot of the Falcons FX kits in bags circulating after the double kit launched a while ago, one of them should get you most of the way to completion. The few parts missing could either be scratched or substituted. There is an excellent 3D printed gasser front axle out there now that I'm eager to try, for example.