oem brake booster vs geo

i know everyone says its samller ...whats smaller the overall dia. cause i have moved my over and now i went from 18's to 20's and now they hit the booster just barely but anuff to gouge a line in it..i thought about geting some 1/8 or 1/4 inch spacers to push the wheels out just a little but since i gota buy a new booster i thought about a geo...

also what geo do i need to get one for...and will my master cylinder bolt to it

I've got one on mine and yes you'll need the master cylinder as well...I did notice a very small  difference in stopping power but I could still lock em up if I needed to...that was with worn out brake parts as well but I'm rebuilding everything right now with all new stuff....I think mine came from a 95 metro