73 340 Compression Test interpretation help

Another point, there must be airflow through the crankcase. The pics jimmyray posted show a breather on the right valve cover and a sealed filler cap on the left. If he were to replace the breather on the right side with the Ford style, and not make other changes, the system would not work properly. The easiest solution would be to put the Ford style on the right side, and replace the sealed filler on the left with the breather currently on the right. This assumes the current and Ford breathers are turn-to-lock and not push-in.