The steel plates from OPGI fit well and the hole is exactly the same diameter as the original.
A number of vendors use generic body mounts designed around a Chevrolet application which does work, but not correct as Chevrolet did not use the same amount or type of bushings as the BOP cars. As far as 68-72 A/G body Pontiacs are concerned, all had 14 bushings.
The number and type of bushings depend upon the body style. The vert or the coupe HD boxed frame uses two bolted bushings per side under the firewall. The coupe has only one bolted and one non bolted (solid) rubber. The #4 bushing just ahead of the rear wheel is also a bolted/solid bushing depending upon application as noted in the service manual.
If you wish to stiffen up the coupe chassis buy the convertible kit.
The best by far are the ones from Inline Tube. They are specific to Pontiac and even include the Chevrolet specific bushing (#7) that is used at the rear frame bar under the bumper.
AMK has the correct hardware kit with the pointed bolts which are far superior to what OPGI offers