No worries on the frame strength, it's a design that's been ridden and raced for over 60 years and millions of miles.
Here is the famous photo of Rollie Free setting the world record for Motorcycle land speed on a Vincent Black Lightning in 1949. He went 151mph on a production Lightning.
At the time there was no other production motorcycle or car that could even come close to this speed.
A few years later this record was bumped to 187mph by Russel Wright of New Zealand, also on a production Vincent Black Lightning.
Russel was a house carpenter who wanted to set a speed record, so he ordered a new Vincent. He contacted the F.I.M, who provided the necessary recording equipment ,then went out and did it.

It's interesting that right up until a few years ago the Vincent from the 1940s was still the World's Fastest Production motorcycle. They were obviously many decades ahead of the pack in design.