The oil pressure sender is #74406-87, not to be confused with a switch, which your bike currently has (which lights the oil light). That took a bit more effort to find than I expected! I only sold an unused one a few months ago, as well!

The oil pressure gauge is 75032-87. According to Ronnie's parts finder it looks as if they both are available.

Alternatively, take a look at J&Ps catalogue for 'oil gauges' and you will see a wide variety of options, especially of the direct non-electrical type, mounted on the engine or cylinder head.

 

This questions are coming up in my mind now that I made this tach fit inside my fairing I'm thinking on putting more stuff in there. Maybe an oil pressue gauge, fuel gauge, speakers, compartments to put stuff in (glasses, gloves, a drink,...).

 

Those gauges you want can probably be bought secondhand, so it is worth keeping an eye on Ebay. Matching ones were made for many years and the number I gave you earlier has the same dial styling. I sold some only a year ago!

Here is an oil pressure gauge, and voltmeter, as examples of contemporary gauges.

 

As Graham already stated running an analog oil pressure gauge is not a great idea if the line were to break a crotch or face full of hot oil is not my idea of a good day. I looked at this as well and have decided to go with the latter model gauge with electronic sender, but it's still pretty far down the list for now. let us know how it goes.

 

I think you mean mechanical oil gauge, not analog...

 

Yes' what Dan said, thanks must have been stuck in the electronic world.
Cheers