I am not conversant with the NJ rules so if my suggestions don't work for there please forgive me.
As already suggested the Mech Tech is a good choice, based on either the 1911 or if you can have higher capacity, the Glock. If you don't own either of those it is not that expensive to build a dedicated lower.
Another good candidate is the Mac offerings from Masterpiece Arms. My brother has one in 9mm and one in 45 and they work very well and are both reliable and accurate and extra mags are fairly inexpensive.
A lot of folks speak well of the High Point. Down side to it is magazine capacity but that might be what is needed in NJ.
Next you have the Beretta Storm which is available in 45, again though only low cap mags are available.
Olympic Arms does an AR upper in 45, it uses unmodified grease gun mags which are inexpensive.
Last I will mention the Kriss Carbine. I know very little about them but it is another possibility.
Of course you can feel free to get creative, below is a SKS a friend of mine converted to 45acp using Glock magazines...