I replaced the original three Datamarine bulkhead instrument faces quite a while ago.
I used Raymarine ST60 : speed, depth, and wind.
The original holes were 1/2" too wide for the new instruments.
Luckily the new ST60 bezels would cover my repair.... so I took some old round plate pieces of frp (that were cut outs from the install of instruments in our prior boat!) and sawed out a center in each one for the new instruments. This produced a ring with 1/4" sides. I epoxied those rings into the old openings.
The adaptation is invisible from the cockpit, being concealed by the instrument face.
This also proves that you should never discard stray pieces of frp material. Lacking such a source, you could source some G10 plate from McMaster Carr.
After some puzzlement over just how to "shrink" a hole, this was the solution I came up with, and it still looks good, i.e. invisible. Note that if no can can see your fix then it passes the test.
Regards,
Loren