Is it possible to change the Rev limiter on a Thunderbolt V ignition?

Can you use Thunder bolt VI ECU in place of a V with a carb setup?

Im trying to achieve more rpm.

Click here

The board has a nice search function This has been talked about quite a bit and I think the link I gave you has one of the better solutions.
Just remember no limiter and knock sensor could be trouble. You may want to re think removing the limiter on stock 500's and replace the whole module with aftermarket adjustable limiter ignition you will loose the knock sensor but have the limiter control if you pop out of the water and miss the sticks!

Crane has a marine spark box that will eliminate your t-5 and keep the stock distributor and knock sensor. It has advance programs built in and an adjustable rev limiter.
Get it at Summit Racing. Keep the stock stuff on there for a backup. It should be plug and play with weatherpack connectors.