Peter,
Definitely don't use that 2" CS gauge. Shouldn't mix degC with degF gauges, and a 2" gauge just won't go in a 2⅝" hole
.
I might be wrong, but
surely those 2⅝" CS gauges are rebadged SW 2⅝" gauges?
If it you really don't want to mix CS and SW gauges (even though I think they are the same gauge), consider that 'back in the day', they mixed and matched to suit what was available at the time, and also what suited individual driver's requirements/preferences
Cheers,
Glen