Guage conversions

Ok I guess I am not asking my question right, Anyone know what size of guages I would need to fit the stock openings as these appear to.

I assume this person shaved down the bezels on the two large openings to get the guages to sit flat.

Did they just remove the whole Cluster and just keep the grey dash part?

Did They use the old wiring, or re-wire everything through the firewall?

I did some more research, and this pic was at the bottom of a post by FSTFISH66. I do not know if this is his handywork or not.