Brand new '72 Demon!

So, I joined a little while back and finally got my A-Body. a '72 Demon midway through pulling out the slant 6 and dropping in a 340/727. The 340 as far as I know is stock save for the J-code heads. Both the 340 and the 727 are mounted. It just needs wiring, a drive shaft, a sturdier rearend?, and to my horror I found I need new floor pans after I got it home. Any help or comments anyone has will be greatly welcomed! Thank you all for having me.