Allow me to disagree with my brother, ChevyBoy 68's comment "Whatever you do don't buy rubber".
Here's some reasons rubber might be a good choice:
1) Easier on components.
2) Lasts a good while...I bet half of the firts gens still have the original rubber front end bushings (30+ years).
3) Smoother ride...it's like letting 10 lbs of pressure out of your tires compared to the poly.
4) Much less expensive
5) Don't squeek...and when they do, it's time to replace them. (I currently have a 69 with polygraphite a-arm busings that squeek like a pig in heat...also every rattle and interior squeek are much more noticeable with poly).
There are many as myself, who believe OE rubber bushings are the best choice. Yes, we give up some handling performance, but the trade-offs aren't worth it to us. My opinion.