Rapco can't put any serious seal on that pump that would last any
time because it's a dry pump, and seals need some lube. Rapco does have
a pump to fit the under-nose mountings like the O-200, where oil tends
to get into the pump, and that pump has a flinger and a drain port to
keep oil out.
Washing the engine with solvent can also wreck the pump. It
needs to be covered during spraydown.
We use Rapco pumps exclusively on five airplanes, and have no
trouble at all reaching 1000 hours.
Basically, your oil leak need fixing. Oil leaks represent an
attraction for dirt, which does no engine any good, and they're a fire
hazard. And some oil leaks are warnings to fix something before it
blows off completely and all the oil is lost overboard in flight.

Dan