Does anyone do a poly replacement for the standard rubber top items?

There must be some universal polyurethane spring isolators/locators available. Maybe your best bet would be some sort of Alfa Cup car for near FIAT specs.

I'd imagine its only a case of diameter and desired thickness, aling with sufficient clearance for the bearings on the front. Hell they might even do some with tiny ickle holes in so the springs don't sit in a pool of water at the back and rust like hell.

That's a good shout. I'll report back should I find anything.