Chad...The difference between the 7's & 9's is obvious. Fit that tyre on an 8 inch rim, & it may not look too bad. When I was involved with A-Sedans, I (much later) found that a couple of the fast drivers ran 9 inch wheels, only at selected events. Even ran large motors, but that's for another thread.
I can't speak for early SCCA scrutineering, but I can pass on a mid-70's experience. We were at Laguna Seca for a T/A event, with a car that had been, also, running IMSA. The SCCA official (whose name escapes me now) went up to the driver, exchanged greetings, etc., then merely pointed to the left rear corner & said, "Just cover up the Camel decals, & you're set."
Question for anyone, "Any truth to the story that in the early days of T/A (when post race weigh-ins included a spare tyre) Penske tossed in a water filled tyre?" Robert Barg, where are you ?.....yes, I followed you here from TNF!