I don't have any experience with Poly.
But I like the ride I have it's not rough.
Also watch out what firmness of shocks you put on. High presser shocks will stiffen up the ride a bit more then low pressure.
It all depends on the how you are going to be driving it. Street cruiser make it comfortable. Road racing, make it the best possible.Good luck.
66' 289 2v, C-4, bench and a/c