This talk of forlorn early Fox Mustangs reminded me of one I found a few years ago, forgotten in a collapsing, abandoned building.
For early Fox Mustang fans, it ticks a lot of boxes; Black GT with red guts, 5.0 HO, and a 5-speed.
I second both suggestions above.
To speed up dry times when hand brushing, (assuming you're not painting bodies), consider giving Tamiya (or similar) lacquers or acrylics a try.
Cool project, both this and the transporter project. I'm watching.
I've been planning a similar build, but stuffing the Revell kit into an MPC '74 Cuda.