.... I just chucked it up on my lathe with 11" swing and it clears the ways with some room. I think it may be able to be done on a 10" swing but likely no smaller.
What model motor is that head from...that lip around the one edge looks odd to me ? Maybe I just never noticed it before. Can you get away with machining just the head gasket portion or will that lip contact something. It must seem like it takes forever when your feeding slow across that section...tick....tick....tick....tick.
I would machine it off too like you did...well...just because it would bug me if I didn't.