The thread in the filter block is 1/4" British Standard Parallel Pipe (BSPP) thread, not British Pipe Thread, which is tapered. As such, an adapter fitting needs a sealing washer.as for the oil pressure sender. This link is helpful: . https://jaguaretype.wordpress.com/home/technical/mechanical-oil-pressure-gauge/
You can find British fittings at this site. Inexpensive compared to McMasters…also a longer thread, which is helpful when fitting the sealing washer… Sealing washer available on this site.
http://www.hydraulicsdirect.com/British-metric-fittings-s/1914.htm