A friend of mine in the late 60s had Super Hawk 305. He was taking a machine course in college and he used the Honda as a project bike
The first things he did was to remove the cylinders and pistons, then remove the cylinder liners. He then bored ot the aluminum to accept the liners of a Honda CB350. He carefully fitted the bigger pistons in and ported and polished the heads, then put in a precision machine roller tappet cam of the most radical he could get. He fed the thing with a pair of Amal GP carbs from a 650 BSA race bike. The engine would stumble and die below 4,000 RPM but came alive at higher RPMs.
When he let me try it out he said be careful, it comes up on the cam at 11,00 RPM, try to shift at 14,000 RPM.
I thought he was pulling my leg but it was true The engine burst into power at 11,000 and I had to shift quick to avoid going over 14,000.
He took it to the drag races and it could turn 104 MPH in the quartermile. He did not to my knowledge, put sprockets on it to try for absolute top end but if he had, it would have been awesome for a Superhawk.
I moved out of state shortly after that so I never knew what became of the bike or what he did with it later.
I know that some of you will claim that it couldn't run with those giant carbs. I tended to disbelieve it until I saw it run.
Then I thought about it. A 350 engine at 14,000 RPM sucks in as much air as a 650 at more than 7,000 RPM.
It showed what the real potential of the Supe hawk engine was if carried to the extreme.