Model A, why didn't you mention Dave Kostella's car by name? We are all friends here. My infamous American Austin, I won't call it what everyone else calls it, was rebuilt 3 times because of the SCTA rule changes.
Mark Dee's and Dave's cars were already running in 1969 when it was started.The Minall-Barrious roadster first showed up with a 29 Ford grille shell, which was allowed in 1970. It had a 12 inch stretch which also in the book at that time. Marks and Dave's had longer than the 12" stretch and both were put in modified even tho Marks had set a record in Gas Roadster.
Barrious had to put on a "factory" shell the next year much smaller than the 530". It ran for a few years and I bought in 1981. By '83 I had rebuilt it the first time, The grille shell rule was change to 530" no matter what the car. At this time I put the rear wheels in the stock location much narrower than a Ford. The hood length was still 12" over stock I used a 31 Chevrolet shell.. After Dave went in the 2 club over 260+ mph I don't remember seeing his car anymore. I had the Dees body for years and now Jim Lattin has it.
For the beginning of the '86 season the rules were changed to 50" rear tread, no rear fenders, no tanks infront of the grille. 3 things made my car illegal. By 1987 the 12" stretch of the hood left and 143" over length was in and I started rebuliding again. The rules have remained pretty constant since then. I brought mine back in '93 look as it is now. 32 Ford grille shell, 143" overall length, 50" tread width, 28" from the windshield line to the step pan, etc.
Ford guys in the past changed the rules to make the demensions similar for all gas/fuel roadsters. very few Austin roadsters were ever built in the whole scheme of things. Guys want Fords.
At this time ALL the current/past running Austins have put some one in the 2 club. Dave Kostella in as a modified along with Amos Beard in his. Mark Dees, Bill Goldman and Patrick & me, JD, Tone as Gas /Fuel Highboys.
Wilson is already in th 2 Club with his Hudson powered cars but I believe he will also go over 200 as a rear engine Austin.
Austins are actually wider than both the 27 and the 28/29 Fords at their widest spot. They are short and are hard to meet the firewall/step pan rule in Gas/Fuel roadsters. But it is a choice all make.
I have pictures in my garage with Chuck Potvin sitting in Med Healy's Austin roadster in the 40's. It had a 32 Ford grille shell and a Chevrolet 6 for power. So nothing is new. Good Luck