Personally, I don't see why not .... Plenty of material in that area to accept a larger bolt.
Just make sure you replace the pinch bolt with a similar M14 high tensile one
As for the mushroom locking bolt .... I was thinking along the lines of a M6 bolt, I guess M8 would be better.
Star washer & a nice bit of Loctite & the job will be a good un
