I appreciate this is an old thread, and it’s a good write-up. I’m concerned that over tine you will get cracking where the adapter(s) connect to the block from vibration. My solutions would be:
1) Use a sandwich plate adapter at the oil filter with 1/8” Npt Fitting for the oil pressure sender. More expensive, but lots of options including Mocal.
2) If the warning light is just an ‘idiot light’ wired directly to the pressure switch, just replace that with a single Male-BSP to F-Npt converter (3036-02-02)
https://shop.hoseandfittings.com/cat...13ac8c2&LINE=1
And put your pressure sender there. The idiot light would never light, but who cares if you have continuous pressure monitoring?