use the stock bumpstops they are fine as long as they are still in ok condition..
If your useing lowered springs cut the bumpstop down a tad, this is what I did, there is no problem...
make sure you use boots though, they are the rubber sleeve that covers the strut, the shiny rod of the shock absorber, you dont want dirt getting in there it will shorten the life of the shock by chewing the seal out..
I used generic CV boots from repco, $12ea easy to get... or I also though I could use a bicycle tube cut down, I used some wire straps to make sure the boots stay in place protecting the strut...
It really is an easy job replace suspension, do it yourself save a heap, feel good afterwards...
get an aligement afterwards to be sure its all sweet... it your lowering def get an alignment and give thought to camber adjustment parts, there's a whole heap more info on that subject to be learnt... search