My demon project . How would you build it ?

I would say, put whatever small block is closest to running in it, then whatever Tranny seems to be in the best condition and throw that in there too..... of course keep the 8 3/4. Keep one other bare block small block (340 if you have one), sell all the other parts/motors/and trannys.... then while you're cruising the demon now, you can build up a fancy stroker and possibly a 5 speed with the extra coin left over from the parts 8)