A friend of mine bought one of these tanks to fit to his M20. Of course the rear mount holes are out so will need fettling.http://www.ebay.com.au/itm/250986186921?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 Still don't know how to highlight ebay listings when i copy and paste?
Yes that is an oil pressure indicator at the bottom of the panel. There is a guy in Holland making pattern ones. There is a short oil pipe going through the hole in the tank. Beneathe the tank there is a banjo fitting to be able to detach the oil pipe from the pump to the banjo in order to be able to take out the panel.
It connects to the engine in the hole just below the timingcase. This hole is mostly plugged but this plug can be replaced by a hollow plug which takes a banjo and bolt. The same connection as when the indicator is placed on top of the timingcase.
The chrome isn't brilliant but after painting it should look acceptable. The rear tank mount holes dont line up, so we will cut and shut the two metal strips forward by 1/4 inch. They musn't have a frame to check the fit!