Proper GCC flags??

[Andrew]

Hello Im on a big project right now. I've copied all src.rpms found on the YDL4 source CDs and im about to --rebuild them all. I want maximum optimisation ( -O3 ?!) as much as possible, squeezing as much speed as possible. You get the drill. I searched quite a lot but I couldnt find any suitable informations.. :(

My questions are all about GCC flags and friends.
Q1: What would be the best flags to pass to GCC for my computer( -mcpu, -march.. )
Q2: Where do I put them up so I wont have to type'em for each and every packages and I want them to be the default flags...

PowerMac G3/300