[dsraven]

good catch there whitedog, forgot about those hidden bolts behind the flywheel.
after the flywheel is turned ask the machinist how much was taken off. you may need a shim behind the flywheel to keep the geometry right for the release brg. the machine shop usually keeps those in stock but maybe not for an old engine like this.
ask the shop if they grind the flywheel or use a cutter. grinder is preferred because the cutters can bounce over the hard spots and cause an uneven surface. also ensure they do the before and after measurement so they know how much they took off rather than " I think" statements.
wear a particulate mask because the dust from the clutch wear is carcinogenic. I usually use an old pump spray bottle to wet things down so there is no dust.