I confirmed the nick jumbo turret will not fit the barbet ring of a henglong or taigen.
So either buy nicks hull, or a better idea, sice you have to build up the armor on the sides any way, buy a tamiya hull and rotation kit, slab on the extra armor cut out using the m4A3 hull you have as a pattern and lengthen the tamiya hull appropriately, then get the engine deck conversion kit from nick for the tamiya to make it a A3 hull. This is probabyl better than the urethane hull as it would be more sturdy in the long run but not as fast a build.