I am thinking about taking out the 283 and powerglide out of my 66. and replacing with a 350 with a th400 tranny will the driveshaft hook back up or will it need to be replaced or shortened or be to short? What do you think about a powerglide with a 350?

I would build a dare-to-be-different combo. Build that 283 with a roller cam, Trick flow heads etc. And keep the glide. I knew someone who ran in the high 12's like that.

You'll need to have a driveshaft made. The slip yokes are different and it will need to be shorter.