Here are a couple photos of where I am, and what I want to accomplish by tapping this hole. Ignore the threads in the 3/4 hole - those were surface cut with a 3/4-14 NS tap (not pipe tap) ...before I knew that the hole was undersize for a 1/2 NPT plug. They barely scratch the interior diameter.
First photo shows location of the drain hole in the 270 block.
Second photo show the 228 oil filter canister and drain line that was stock on this 228 (41 GMC project.).
I want the option of using this type of stock filter by either tapping and installing a reducer to fit a 3/8" brake line nut...or plug this 3/4" hole, and drill and tap for a full flow filter system on the other side of the block.
