Thanks you guys, I really appreciate all the input. A number of alternatives to consider, but I will probably modify the pan and maybe move the TH as well. The liner is a 1/4-32 White Lightning, so if I were to replace it with a plug made from a 1/4-32 bolt and then drilled for a 3/8-32 next to it, how much of the plug could I safely drill into?
Also, I sawTom Snyder's vent coning tool on the internet a while back, but now I can't find it. Can anyone steer me toward one?
Thanks,
Dick