Oh boy...
1. Aluminum and powder coating are mostly bad ideas. ALuminum needs to be chemically treated before it gets powdercoated to have ANY type of good adhesion.
2. IIRC, the 4500 uses a Hydroformed top tube (albeit not the best version) but hydroforming uses EXTREMELY thin walled aluminum, and may lead to more of an issue with powdercoating.
3. Why are you getting it powdercoated in the first place?
4. If you're going to be getting it powdercoated, you should probably just take it into the shop and have them pop the BB out of there for you, because you'll need to have the threads chased in the BB after the powdercoating to prevent any binding.
5. Chasing the threads is NOT optional, and you'll most likely need to have your headtube reamed and faced as well.
6. Does this frameset have a removable rear derailleur hanger? If not, you'll need to have that chased as well (which is basically impossible without destroying it).