Sadly we don't have lathes in our workshop so isn't going to be happening anytime soon, many a broken throttle body in the process so Ive heard though as the tolerances are so close?
I'm glad you've posted that image actually as it's reminded me to ask, whats the purpose of the smaller vacuum outlet that runs down to the side of the airbox? I know the larger one runs to the purge valve which I've blocked up as it's now been removed.