Nice easy project mainly because i had already got the gauge years ago and it has been in a garage draw ever since. A couple of 3mm holes under the dash out of sight to hold the gauge and a t-piece from the local car accessory shop together with some bits of thing i already had lying about completed the job.
Instructions how to use the gauge and what the different reasons mean by courtesy of mgb-stuff at http://www.mgb-stuff.org.uk/vacgauge.htm