You haven't told us things like what model KHS do you own? What length shock is on it now?
If your shock is shorter than a 8.75, I wouldn't go bigger as that can make your suspension do funny things. The only time I've really seen people change shock sizes is from longer to shorter (ie 9 to 8.75 with the same stroke length) to get a more slack head angle.
If you're trying to put a longer shock on to get more travel, it will probably make the bike handle poorly.
it's the KHS DHSO model with a Romic 7.25 rear shock on it, the one i am considering putting on is a Manitou 8.75. I'm wondering if i should drill a hole to mount the new shock and where would be the best place.