Many, many dive watches have survived water intrusion by receiving a full service.
The largest opportunity for water intrusion on rep panerais is a stem that is cut too long causing improper seal against the tube, or a damaged Crystal gasket. The more common issue being the Crystal gasket. If you don't have these issues, your watch should be VERY water proof. The only way to know for sure is a pressure test.
You introduce a new variable with the pushers, but again the construction on the 187 pushers is very sound. Get it pressure tested and go have a dive. Let us know how it goes!