The only issue(at this point in my mind...) for the sheet after it leaves the main blocks is; forward or aft, of the traveler. Having studied several similar boats, I've settled on aft. I'll likely move the traveler track(and turning block), farther aft in the new cockpit(eliminating those small lockers). That will move the whole sheet aft a bit with the traveler. I'm limited by the mizzen mast.

Here's a similar set up. The winch takes up space in the cockpit, I'd rather keep it outside.

As far as height, I'll have a surplus of rise from the turning block aft of the traveler to the new mainsheet winch. In fact I may have to raise the turning block a bit(like this lower photo - turning block mounted on riser block).

Here's one with the turn forward of the track. Having played with a similar mock up - forward of the traveler - I prefer the turn happen behind the traveler. But I like this winch location - outside the coaming. Ironically, my idea to get the cleated end forward from the winch in two ways, works better with a non-self tailing winch than a self tailer. Save a thousand!