Hewland Hub Question

We are having a Hewland Mk4 5-speed built. The guy who is building it has come across some mismatched parts and he is looking around to figure out what is mismatched.

He said that on the 1-2 hub for a 5 speed, the machined portion of it seems too short. He showed me that the length allows for a 1/2” width gear and a 9/16” width gear. I says he’d prefer to fit two 9/16” gears rather than find some narrow gears that he says are very rare. So he is hoping to find that there is a longer 1-2 hub for Mk4 5-speeds.

Is there a longer 1-2 hub? Does anyone have a Mk4-6 1-2 hub available to measure to let me know how tall it is, and how long the machined portion is?

Or are we relegated to narrower gears?