Why do you insist the pure gold are too hot when I've shown you the pressures plus I have used them in mine with no problems. You plan on shooting thousands of rounds.
Though the Tobin would probably only get out once or twice a season, these Kent Pure Gold cartridges are at the upper end of the limit, are they not?
Do you consider the paper shells with pressures of 6500 psi to be at the upper limit?
I have no qualms of shooting the plastic hull gamebore through the Tobins with pressures of around 7800 psi.
As mentioned, these guns have had shells put through them through the years that far exceeded 7800 psi.