Surely you're gonna wait and see what the new 45mm is like first, i.e. a few more pics and feedback before making a decision?
Also you're not gonna get much of a franken UPO with new parts for $500, the rep plus gen dial and the budget is practically blown. Maybe search for 2nd hand parts and you'll keep a reasonable budget.
btw there is/was a franken UPO on sale in the sales section yesterday for not much more than you are asking and it had almost everything modded on it, great rep.
I would wait on, if the aR on the new C-45 is not as good as the 42mm then they well might get it corrected for the next batch after cny.