NEW INFO ADDED - NOT NECROPOST
John-
I live in CA which is notoriously tough on the little rifle that wish it could. And there are legal ways that I can have my AR in an A1 configuration. Yes, even with all the "evil" features intact.
I'm not sure what the exact laws in NJ are, so you should take a look at them. IN DETAIL. In CA, the Courts ruled that governments cannot just say "all assault weapons" are illegal. There are SKS, AK's, M15's, etc for sale here in CA. And it's frustrating when I see one cheap out of state and want to buy it legally. (FFL transfer, etc) People are so convinced that they know my state's laws that they refuse to sell them to me.
"Oh no- you guys can't own this there..." Says three different sellers at a recent gunshow I visited. Go figure, the most ardent gun owner is the anti-gunner's best friend. I told them so as well. I never ask for anything illegal. I enjoy my freedom and don't want to room with "bubba the butt raper" for 10 years.
Just find out your laws. Most likely they have a list of firearm makes that are not allowed. You will likely be able to pair your Colt A1 upper (not a firearm- so you can buy one online and get it shipped in the US Mail) with a NJ legal lower to have a legal A1 for reenacting. Just check out your laws very closely. If you need to have a fixed magazine, there are legal ways to add that to your retro lower.
good luck.