You won't be removing anything more than the swing arm and clutch slave to drill the weep hole, so there are no seals that will be accessed for replacement during that work other than the gearbox output shaft seal. I'm not 100% certain about the sealing arrangement on the clutch push rod forward of the slave though, others may be able to advise. On the clutch slave cylinder, take the time (and trouble) to investigate the possibility of getting some fresh grease into the thrust bearing that the clutch push rod presses on, it's located in the slave assembly. This bearing is the part that fails (siezes) and causes the slave cylinder piston to spin in the bore, wrecking the cylinder bore and piston/seals, then the fluid leaks out and it's alll over. So if the bearing failure can be prevented the weep hole will never see fluid, and that's what we all want.