Well that sounds like a plan... I didn't realize NJ would allow a reamed out magwell that accepts 30rd mags, so your solution makes everything much easier and the gun really isn't terribly neutered since you're just welding on the slant brake that most AKs have and who cares about the bayonet lug (except for show). I'd still rather have the evil version but you've kinda got the best of both worlds since you can have it in NJ yet still use 30rd mags in non-ban states.
And honestly I'm thinking of getting some 20rd mags since 30rders are heavy and unwieldy. On the other hand I'm toying with the idea of fixing my bayonet lug to make the rifle fully evil!
(ETA: Except for full auto of course...)
Anyway, good luck with it, and let us know how it works!