Motorcycle Repair: EVO Engine oil bleeding into primary, engine crankcase, crankcase breather

Question
I have a 1989 FLHTP 1350 EVO certified police special, and as far as I know it is stock.  It was an old Indianapolis police bike.  It now has 55000 miles on it and it runs great except for a nagging problem of bleeding engine oil into the primary.  It would have to be through the main crank seal.  I have installed new main crank seal twice, did not change the seal carrier.  Did the job twice, once in each direction at various suggestions, behind the alternator rotor. Some say it could be the oil pump or porous cases?  The crankcase breather had been disconnected from the air cleaner housing but it is open at the lower rear engine case. Since I really just started having the problem about 6000 miles ago I really do not suspect porous case even though I read they were a problem with 1989 HD Evo. Bike had 42000 on it when I bought it in ‘01. problem did not start until '04. Looks like it still has original oil lines.  I have never flushed the oil tank, and I suspect possibly a return lines sludged up or partially obstructed, thereby over pressurizing the engine crankcase and pushing engine oil past the main crank seal into the primary. I also have replaced the rocker box seals using cork when they started blowing oil about the same time the primary problem began.  The rocker covers still blow oil too after that repair which leads me to think over pressure in general in the crank case.  I have been advised by some to change the oil pump.   Should I replace the oil lines and flush the tank for starters?  I have one of those small bike jacks and could I have damaged the oil return line where the lines run underneath by the frame, causing it to be hard for oil to return to the tank?  I don't see a visible crimp, but sometimes that doesn't mean the line is not internally damaged.  Should I check the oil pressure with a gauge?  I drain about 4 oz of oil from the primary for every 150 miles I ride, then top off the main oil tank.  After being into the main crank seal twice I am hesitant to set off in any direction. Have you heard of some of the causes and remedies for this problem?

Thanks for your opinion and any suggestion you may have.
Coaldigger in southeast Ohio

Answer
In 89 Harley had a problem with their cases. oil would weep between the steel insert and the alum case and fill the primary case. There is no repair, the only thing you are going to be able to do is replace the cases.
Good luck and happy riding
Mike