A few years ago I posted pix of the pistons from the Yellow Peril, a 73 145E,
which had been run in the Arizona desert without an air cleaner. Several pistons
were in similar shape.
I'd recommend that you measure the cylinder very carefully before going back
with a standard piston, as the bore may be oversized or otherwise damaged.
Ring breakage can have a number of causes some of which include an unbroken top
cylinder ridge, insufficient ring end-gap when installed, too wide a ring groove
in the piston or ring seizure from other causes. The ring might have been broken
on installation due to faulty ring compression or too rough handling on installation.
In any case it is hard to imagine that that much damage to a piston would not be
accompanied by at least SOME damage to the bore.
--
George Downs, Bartlesville, Heart of the USA!