That spot would be perfect for an oil pressure sensor, it runs up thru the engine to the oil filter cavity. I used it as a feed line to a oil cooler I fabricated and drilled and tapped a return line hole in the side case above the oil filter. The biggest problem with using the bottom connection is Suzuki used a strange thread, M14X1.25 as best as I could figure out, in that hole. I ended up making a hose n1pple out of an extra plug, couldn't find anything with the proper threads. Drilling and tapping the side case was easy enough, there is plenty of metal for threads and the entire cavity the oil filter sits in is pressurized. Can't help with what type of sensor to use, something low pressure like a fuel pressure gauge has been recomended.