If the OP's plug was sealed with loc-tite, a little heat to the plug will melt the loc-tite, and it should come right out. I run into that stuff a lot with pressure washer pipe fittings. You cannot budge them cold. Add a little heat and they almost fall apart.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission