questions about ebay 347 stroker kit

How aggressive motor are you trying to build? Not a bad setup for a 350 to 450 HP setup. (IMO)
I don't like cast (crank) for the higher HP's and they may be just fine.
I'd question or research the KB pistons and where the 3rd ring intersects the wrist pin if at all. Some pistons have been known to leak at this point resulting in higher oil consumption.
KB is a reputable name however and may not have these issues.
What heads are you going to use, he names most of the ones that aren't going to work which are most of the bigger names. You may have to end up flycutting the pistons to make them work.

I've never heard of Prime One cranks and rods.