The later coupes, like mine, have a battery voltage gauge instead of oil temperature. I've seen a few temperature gauges and ones that come with senders too, but not sure how or where they would fit on the coop.
Paul at Motormech was trusted with the installation which involved drilling the sump to fit the sender unit. Then it's a case of running the wiring through to the gauge and sorting power supply. Now I've seen how it's done it's do-able by most people - except for the sump drilling.
As far as gauges are concerned, I'm old skool with the "you get what you pay for" viewpoint.