S10 control arms question!!

ive got the Kustom Works uppers and lowers coming to me right now. The reason i went with new arms was to run a bigger bellow bag with no problems. i know u hafta cut the hell out of the spring pocket with the stockers in there, but what needs to be done to run a 2600 bag up front.

also, how hard are the arms to install. ive seen people talkin about shimming the arms, what is that and will it be needed.

all i can think of man is to cut the pocket out until it dont rub. and for the control arms the shims are for the camber and caster it is for the wear of your tire and you just need to take it to some one that does alignments on them.