What options do I have when replacing my fork's elastomers?
I had an elastomer suspension a lot of time ago, and did my own maintenance on the elastomer compartment. I would not take a fork like this and put springs inside. Bike suspension elastomers dampen the motion of the suspension in two ways:


They expand laterally and generate friction against the inner walls of the suspension;
They have a natural visco-elastic mechanical behaviour, that doesn't let the suspension "spring back" too fast.


With springs only (and no dedicated way to control the rebound), the suspension would become too "wild", I'd say.

I think you should take any elastomer kit that fits inside your suspension, with enough lateral clearance, and use it, no fear. Micro-cellular urethane (MCU) was the topmost material used in bike suspension elastomer (before becoming almost obsolete).

It is important, too, that you put them inside the fork with lots of grease, and specifically LITHIUM-FREE GREASE, so that they don't chemically react with one other. Most probably, there are specific suspension greases in bike shops.

Hope this helps