Chicane67 has mentioned using a spherical bearing in the front spring eye with good results.
It's hard for me to believe that they work that well on bumps that "thump".
What works for one guy, would drive another guy nuts.
My solid bushings were pretty good on a smooth road but you could feel each and every phothole, tarstrip bump like someone hit your seat with a sledgehammer!
As far as Polly, I don't know. There is "stiction" but there is very little rotation of the spring to cause that problem. They would be stiffer than the rubber but I don't know about the ride qualities.
It seems someone posted here about them being kinda rough riding?
I think a stock bushing with a polly insert on the front and rear sides of the bushing would be neat.
Take a rubber bushing and drill one or two holes ahead and behind of the bushing and instert polly or plastic rods.
This would leave up-down stock, fore-aft stiffer.
Check my web page for First Gen Camaro suspension info:
David's Motorsports page
First Gen Suspension Page
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Chev 350 Can-Am Vintage Racer
[This message has been edited by davidpozzi (edited 10-26-2001).]