That chart tells me, a GT1 car has to run a 1:03.517 to even match the GT4 record at 1:06.013.
That's 1.209 seconds the PB for GT1 needs to find, or be in equivalent of current RAW times of the SGT class, but with a GT Car with PAX...
Even my PB in GT1 is 2.379 seconds slower than what's required to match the GT4 record with PAX. But hey, if we need participation awards via math more than driver skill to make everyone happy, maybe Road Racing is calling next year.