hey there, im not real sure but if your trying to mould something your self try asking a seat manufacturer. if you just need a foam try getting a universal foam block and carving out the shape you need out of it.
http://www.vmxunlimited.com/ sell universal foam blocks and then you shape them to suit your needs.
i find my local auto upholstry guys can repair or re-make my seat foams no problems at all. i had a PE 250 seat foam that was shaved down over 1 inch by previous owners (short legged buggers like me
) and i got a local guy to build it up to the correct level with no dramas. nice job.
also ask
http://www.vintage-suzuki.com/ they have foams moulded and can probably help. what bike is it for? chances are there is a maker already making foams for your bike