Assume that you, like me, have the bare bones of a '68 Charger shell that you got for pennies and that looks like it's been Duke'd once or twice. Now assume that it is so gutted that you want to build an open-track race car out of it, but you want to do it for really cheap initially, adding to it later if you get hooked. Also assume you want it to be reliable, ie, not have the engine blow up after a few track days.
1) Install a rebuilt 383 Mopar that you have sitting around, requiring some expense to make it complete
2) Install the very used 400 and 727 out of your old 24 Hours of Lemons race car
3) Get a junkyard 5.7L Hemi
4) Throw in an LS6 because you have it, even though Mopar guys will lynch you for it.