And so it starts... 340 build

drill a hole in both plugs- for oil as you say but also to bled any trapped air/ air bubbles
some motors you can drill a hole to squirt at the leading edge of the cam/ dist gear
you can drill through the thrust into the main oil galley .040 through the cast iron .060 through the thrust
Engine Builder mag that showed up online today mentions chamfering the parting line of the thrust (main) toward the rear- been doing that for 40 years