Not much progress this evening. I reconnected the computer and checked the instrument monitor was still working after all the moving around it's had. Then I marked out the hole for it in the MIP. It was too late to cut it by the time I was done, so that's a job for tomorrow.
I also looked at radio stacks and ways to connect my real world Garmin GPSMAP 295 to FSX.
There are a number of radio stacks out there ranging in price from a few hundred pounds to thousands. I can't justify a massive expenditure on this, so I have narrowed it down to 3 possibilities.
In terms of interfacing the GPS it seems that this is pretty straightforward to do using FSUIPC. I need to rig everything up and see how it works.