If you don’t qualify for SCTA records, how about going for glory with the FIA??
The current up to 250cc NA records look a little soft at 122 mph (kilo) and 120.116 mph (mile). At least I assume they’re soft since they were set at a couple of British airfields.
[Actually, I've just noticed that the 250cc to 350cc records (flying kilo and mile) appear to both be ‘Open’, and the 350cc to 500cc class are only 99.5 mph (kilo) and 88.7 mph (mile).]
Even the blown records may not be out of reach:
Up to 250cc – 144.2 mph (mile and kilo), set in 1959
250cc to 350cc – 158.2 mph (kilo) and 158.3 mph (mile) set in 1966
350cc to 500cc – 222.6 mph (kilo) and 223.1 mph (mile)
OK, so the last two are a bit more challenging, but once you’ve got the first ten you might be ready aim at 225+mph.