How is the flex plate balanced?

[sleeperstang]

You guys couldn't have posted this topic at a better time.
I'm having the same problem with my car. My 289 engine has just about died on me due to vibration problems which I think have caused rod knock. I'm planning on buying a rebuilt 302.

This is where things get confusing. Say I get my 302, and it's a 60s block, so it uses a 28 oz imbalance. My mustang currently has a C-4 tranny, but in the garage I have a T-5 that will go on some time in the next year. I will have to go with a flywheel from a newer mustang, which I already I have. I know that it will have to be machined down to 28 oz imbalance. The question here is could it be swapped and not have problems without having to take the engine out and have it rebalanced.

I guess my question breaks down to, is the imbalance swappable between automatic and manual balance factors?

Thanks!