On my stock 500hp carb rev limiter how can i get a few more hundred rpms out of them.

Maybe replace the distributor with an aftermarket one, like an MSD???? That would have to fix it, there is nothing else that can limit the motor (on a carb'd deal).

Not true, the rev limiter is in the Thunderbolt V module on that motor. It cannot be adjusted. The distributor is simply a Mallory marine distributor with a hall effect pickup. I tried to find another module to fit the Thunderbolt V when I did mods as rssteiny and could not find another module. Maybe someone on the board has another option for modules to install in the stock TB V.

I installed my buddies extra thunderbolt IV module that did not have a rev limiter to go to the dyno so that is an option but that will end up with no rev limiter at all.

I ended up installing Crane HI 6M modules with the stock distributors. Adjustable rev limiters and ignition curves. Works fine. Don't know if you can still get them so maybe MSD is the only option.