[Land-speed] Christmas Query

[bobbyhotrods at comcast.net]

Merry Christmas everyone!
I've got a question about plugging holes in a block. The motor was purchased assembled and has been run; now it's time to change things over to a dry sump. The holes that need to be plugged are 3/8" and 3/4", the block's cast iron, and I'm not tapping them upside down with a shop vac going unless I have to.
I've got an idea or two that would work I suppose. The plugs can be permanent. I've got a lathe. What say ye, cognescenti? Thanks, BJ in the Bean, where it finally thawed