I use the Loctite 5 minute Epoxy that comes with the mixing tubes, makes life easy as you just put on a tube and squeeze the double syringe, and the end product is an almost perfect 50/50 mixture. Do use rubber gloves and tape off everything you don't want to epoxy, as it does tend to run a bit until it starts to set up. As for the waterproof factor, once it's hardened you will not have to worry about it. Only drawback is it requires lots of heat to remove if you do have to move it so do several test fits before actually epoxying the components in. One trick I do on fiberglass blanks is to make a line on the spine from tip to end of the blank with a china marker, then make my tape arbors and copy the line onto the tape and onto the reel seat with the china marker. Then when I put the reel seat on with the epoxy, I line everything up and when it dries, everything is lined up and then I can wipe the china marker marks off the reel seat and proceed from there.

Good Luck

Matt