replacing thermostat, (spring, poppet required?)

[KurtG]

I am replacing parts of the water pump and thermostat in a '86 Mariner 40HP 2cyl/twin carb. The parts for this model are very difficult to find.

I was going to replace everything in the thermostat housing but the supplier has indicated that the spring, poppet and grommet that go along with the thermostat are discontinued.

Should I be oK merely replacing the thermostat and gasket and reusing the old parts?

I am going to see if I can find the parts elsewhere in the interim.

Thanks-