I was able to get in contact with Airsoft Depot, and they'll have the $99 DBoys M4 metal body in stock at the end of May. I'll just leave my current CA plastic body in its current state until then, and do a body replacement after ordering the metal body.
I now have two questions on AEG disassembly:
Is removing the V2 gearbox as easy as shown in this video on a JG M4 S-System? How to- Take you Ver II gearbox out of M4 Gun Body - YouTube
Would I need any special tools (like an AR-15 Armorer's Wrench) to properly remove the Classic Army M15 outer barrel from the top receiver?