I don't know if McKerlie Millen is setup to bore a CB750 block.
To do it right you need a
boring plate to mount the cylinder and apply clamping... so the cylinder is in the correct shape. A motorcycle boring plate has a smaller center to center (cars/trucks have a cooling jacket between each cylinder and are usually more widely spaced) so a "car" boring plate won't really fit.
You CAN bore it without the plate, but it's not as good.
Someone that is setup for smaller motors will have smaller boring plates.
In the west end Karasa (KMM) or Gordie Bush. ( I use Gordie... but he is BUSY, VERY BUSY. Don't expect anything like quick turn around. Gordie charges ME $80/hole, but I've known Gordie a LONG time, I was one of his first professional customers in the "70s... but every time I send someone else there, it's not $80, but I bring my own boring plates... maybe that's the difference in price) (it's not).
Bondi can do multi cylinder engines, you bore the holes one at a time.
In '75 or 76 I had Gordie build me a set of BBC oval port heads, with BIG valves, and a port area bigger than a square port head. The ports were so big I had to section two intake manifolds and weld them back together to get the port height. It was a great introduction... he still thinks I'm nuts, 50 yrs later, but will entertain my idiotic ideas. Build something TRULY stupid and everyone remembers your name. (The heads didn't work, they ended up on some roundy round car, where they worked splendidly)
