Kurt, re the Camaro 302 powered Firebirds, I will relate what I have gathered from period reports and publications.
The SCCA was very keen to get as many of the auto manufacturers participating in the T/A series. Their own rules stated no destroking of existing production engines was allowed, in order to meet the 5 litre engine size limit.
As Pontiac had nothing close to the 5 litre size limit in a V8, the enterprising Canadian businessman, Terry Godsall proffered a Canadian Firebird.
Canada has it's own auto industry, and the Pontiac cars were, in the case of some models, re-trimmed and rebadged Chevrolets. In other words, a Canadian Pontiac could be Chevrolet powered from the factory, and it would be very different from it's counterpart.
The SCCA were perhaps a bit quick to accept that a Canadian Firebird could be had with a Z/28 302, but accept it they did. In 1968 Craig Fisher started campaigning a '68 Firebird with the 302, a Muncie transmission, but followed up by a Pontiac rear axle.
This became the first of a two car team financially backed by Terry Godsall, The second car, driven by Jerry Titus, was an actual Camaro, cosmetically altered to look like a 68 Firebird. This car was initially built by John Ward.
Around this time Pontiac Division knew they had to build a 5 litre engine, and work began on a 303 cubic inch race engine, a version of which was slated to be available as a production option. According to SCCA regulations, there had to be 1000 production units made and sold, for any item to be homologated.
The Pontiac engineers with help from Al Bartz built several versions of the 303, but it is a long slow road to the chequered flag for any race engine.
The small block Chevrolet had by this time, had the benefit of over 15 years of development work, and it had been tinkered with by literally hundreds of engine builders and racers. The Pontiac team of Titus/Godsall were forced to keep using the 302, both from a lack of development point, and the fact that it still had not reached 1000 production units.
But, the 303 did see some track time in the T/A series, though briefly, and without any significant success.
It was 1972 before the 303 powered Pontiac took a chequered flag, Milt Minter gave the Firebird it's win at Mid Ohio.
Here is a pic of my Titus/Godsall built '69 Firebird, it had a 303 in it at one point, and it did start life as a '68 Camaro.