Ok... I just received 5 old pin lock corny's from my dad that are still full of Coke. the problem with them is, only 2 of them have bleeders in the lids. i need to find a way to put bleeder valves into the other 3. can i just drill and tap a 1/4 NPT hole in the lids and pop in a bleeder valve? I'm just not sure if there is enough meat in the lid to seal the bleeder up good. i guess i could tig weld a nipple in the lid and then pop a bleeder into it.... Anyone have any experience with this little problem?