This is one of those money makers for shops, most of which do this
routinely with every clutch job.

In reality, the only time a flywheel needs to be resurfaced is if the
disk has worn down to the rivets and the flywheel is scored.  Even then
the scoring can't be too deep or it is scrap.

Just break the glaze with some emery cloth if there is no heavy scoring
and run with it.  Unnecessary surfacings just shorten the useful life of
the flywheel.  I've had my original '65 flywheel now through three
clutches and one resurfacing and two ring gears.  Those old inertial
starters are murder on ring gears!

--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)

Assisting on Restoration (and spending OPM):
'72 MGB GT (Daughter's)
'64 MGB (Son's)

Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT