Do not use super glue on the CPU! Just stick to themal adhesive, thats mroe then enough to keep a heatsink on. I got an RC revision 25Mhz CPU on my Performa 475 and that's been held on for years.

Keep us posted on your 33Mhz mod, I would love to see how it is done, I might try it myself if I ever have a spare CPU (maybe even 40Mhz!).