The problem with pinholes like that are that the hole from the inside is much bigger- - - -sort of cone-shaped. If one pit has broken through, others are probably close. You'll never get the pan clean enough to do a patch job without removing it, so you need to go ahead and pull the pan, scrub it well with solvent, and inspect it for further damage. Hot oil and J-B Weld don't play well together, even if it looks like you've got the leak stopped when the engine is cold. You'll probably need to braze or weld the hole from the inside, or possibly even cut out the damaged area and weld in a patch.
Jerry
