Gage, the remote oil filter kit was standard equipment on the earlier Expy's with the heavy duty package as it provided an oil cooler as part of the upgrade. Later on, all Expy's got the filter mounted directly to the block. Having the oil filter remotely mounted is a mixed blessing. While it makes removing the oil filter easier, it also puts it in a spot that is more likely to be damaged if you have even a minor accident. Also, the oil "cooler" in my opinion is about worthless as first you are cooling the oil using the hot coolant going through the radiator. Next, when you see how the cooling for the cooler is supplied, it will make you wonder what the engineer was smoking when he decided that setup (ie, both the supply and return come off of the same hose, so, the differential pressure pushing water through the cooler is the pressure drop across about 8" of the return hose, other words, very little pressure, therefore very little flow).
As for mounting a remote oil pressure sensor, it seems to me that there is a threaded plug in the area that you can possibly use. Otherwise, I have seen where people have removed the oil pressure sender from the block, installed a T fitting in its place and then mounted their pressure sender and pressure gauge there.