breather assembly

Engine 44P777-0412-E1 V twin. Running fine until the push rods bent. Replaced heads and rods, adjusted valves, engine fired up and ran fine for a day. I noticed an oil leak so I replaced the pan gasket and shaft seal which in the process turned the engine upside down after draining most of the oil. Reassembled, added oil fired right up and then I noticed oil leaking from the replaced shaft seal. Leaks only when running which made me suspect excessive crank case pressure. While running I pulled out the oil dip stick and felt puffs of air. Engine doesn't smoke. And like an amateur didn't recheck the shaft for oil leaks when the dip stick was out.  The crankcase pressure made me suspect the breather might be clogged because I turned the engine upside down. So I went to order a new breather part number 792185 but its no longer available.   So , bear with me please almost done,  can the breather be cleaned and if so will it function? Can the engine be ran with the oil dip stick loose to remove crankcase pressure which might stop the shaft leak?  And the foam sponge inside the crankcase where the breather assembly mounts is dripping oil.