I turn this argument (new Boss vs modded classic Cuda/Camaro/Mustang/etc) over in my head on a weekly basis: which would I rather sink $40,000 into?
I've owned a lot of different stuff, so hold the fan-boy sarcasm, as I'm still most fond of older Mopars...and I have a few.
But I keep thinking that a cool old car built right will retain more value than a new car, and can be just as effective on a track. I don't need a sound system, A/C, airbags or lots of other stuff the new cars have. And as pointed out, old generally trumps new for coolness & style.
If it was track-only, I'd lean in the direction of a repro body shell with only what's necessary.