Search and replace on existing worlds?

[Talonos]

Hello, all.

I'm trying to eliminate redpower from an existing world, because I'm sick of being dependent on Eloraam's updates. If I understand correctly, if you remove a mod, then all blocks used by that mod are changed to air blocks when Forge detects the blockID to be invalid, correct?

Because I have Redpower world installed, I need to do something with the volcanos and marble pockets or I will have giant air-pockets in my world. Because Minefactory Reloaded has whitestone and blackstone, that seems like a good candidate to replace marble and basalt. Is there any utility I could use to do essentially a global search and replace on my world to make basalt into blackstone and marble into whitestone before I axe redpower?

I was thinking about just changing the config file to change the block IDs. Does anybody know if I make MFR's "bricks" block equal to redpower world's "stone" block if it'll work?

Thanks for the help, and if I'm making any incorrect assumptions, I'd love to know about those, too.

[31trainman]

mdas gold can convert id's for ya.