Have a look at this thread regarding plumbing in an oil pressure gauge to a B20:
http://www.volvoforums.org.uk/showth...t=64030&page=2
I sourced the Smiths oil pressure gauge, some of the smaller adaptors and the braided line for my installation from
http://www.minispares.com
If also fitting a water temp gauge (didn't a 140 have one already?), depending on how you want to mount them, they can also supply a Smiths combined oil pressure / water temp unit.