I would go with your original plan first, change the oil seals. Should be a one hour job. If still having a oil fouled plug, then go to the next step. Oil and compression rings are two separate entities. Bought my 340 Dart and it smoked up a storm. All my buddies laugh while I changed the oil seals, per my above instructions. With motor on the floor (they also laugh), I started it up and no smoke. Rebuilt it anyway, because I was restoring the car and I went through everything. 35 years later and still running strong.