First I wouldn't blame the old 216, chasing down leaks is just part of this old car game, would be same issue with a big block.
Had several leaks from my old 53 motor mainly from the rocker and side cover. Now all is redone and with Permatex #2 which I believe works much better than silicone seal. Also had what I thought was a rear main leak on a 261, turns out oil was leaking around the bolts up front on the timing gear cover and running to the back along the pan lip, a little thread sealer cured that.
And another huge improvement can be made on these motors by going to a PCV valve set up vs the old draft tube.
