To clarify, using three easy outs instead of the right tool is kind of like saying config files are flawed because they have to be edited. Tools are created for a job and it is up to us as engineers to use them properly.

i should really say the PO who stripped the engine bolts with a phillips head instead of a JIS driver made it kind of inevitable. 40 year old machines are interesting.

Most of the screws I have seen are trashed from people using screwdrivers instead of impact drivers. Even with the proper JIS bit the screws will still be ruined if you don't use an impact type tool. There's just no way to apply enough axial force to the fastener with a normal hand tool, even if the shape is correct.

That's what the impact driver is for. I didn't have to convert any bolts to metric, all those are already metric. Only the screws need to be converted.