dip stick and bearings

Two issues, first my 1972 225 keeps shearing off the bottem of dip sticks. I bought the universal dipstick at parts store, changed the oil and then set the dipstick so the 5 qts read at the full mark. I started the engine (also did this prior to the new dipstick so that the filter was full and then let it all settle down) for about 30 sec. Then checked the stick and no problems. Drove for about 15 min and checked, the stick was missing about an inch from the bottem and was bent. I was told in an earlier post that this yr should be about 18" long (which seems correct) and from what I've seen, there are no bends in the stock stick. Any thoughts. Also, have a rebuilt 225 that was never run. Tore it down because the privious machine shop left a significant ridge in the #1 cylinder and I'm having it sleeved. Can I reuse the main and rod bearings, again, never run but was torqued to specks.