More jobs completed today. New boost gauge in - So now getting a reading of 15psi (= 1.03421359 bar) most excellent, looks like the cause of the old gauge not reading correctly was a strange valve that had been plumbed into the piping. Also tidied up all the piping, replumbed using new kit and binned all the old kit.
There isn't really much choice when it comes to single pods out there - all the ebay ones are gash, eventually found this type on demon tweeks, nicely made and a good mounting bracket. Was originally going to place the gauge either through the lower dash or on the mount upside down so that you would look down on it ... however seems better here.
Now the most important job completed today - no more sagging glove box .. removed the clip, did some bending and remounted.
Before (plus notice old boost gauge location!)

After
There's you boys chucking your interiors away .. and there's me fixing mine

- the simple things make me happy.