Why would you bother ordering bolts online when you can run to your local Ace hardware and buy them for less than $1?  Don't forget that you need some kind of spacer to actually raise up your seat.  I used 1.75" long rubber stoppers that I simply drilled a hole in the middle of.

Something make sense to do online.  Others are much easier to do locally.  Take your stock bolts in to the hardware store to match the pitch and pick whatever length works for you.  Too simple!  

It does flex the one piece seat some, which makes lining those side bolts up a little more fun, but I've had it on mine for about 5 years without a single problem.