I had planned on putting the oil sensor in place with a T adapter I bought, however, I had got it off ebay and it's not NPT as it stated, sigh. Only place open tomorrow that will have one is Summit Racing in Arlington, nice little 2 hour drive to get there, but don't have time to wait on shipping before I leave for MV.
The threaded hole in the block (and head) are 12 x 1.75 MM. I had a NPT "Y" I was going to use. I'm in process of doing the same thing. I've got an adapter to go into the block, then the sensor for the gauge. I'm going off the back of the head for the Oil light, there's enough pressure there to make it happy even though it reads less than at the block.