There is a nearly 0 chance of any additional versions being produced from A2A unfortunately.
The main reason is this - it's not that simple. While the L-649/749 is externally similar to the L-049, internally there were significant changes and the engines changed even more significantly. With the L-1049 model and beyond, the Constellation became a completely different aircraft inside and out. About the only thing that stayed "unaltered" between the Constellation and Super Constellation was the airfoil shape. Beyond that, everything else was tweaked, strengthened, improved, or completely redone. The TurboCompound R3350 introduced with the L-1049 was an all new engine. While the cylinder bore was the same, it had a new ignition system, a new gear ratio from the engine to the propeller, a new exhaust system (even from the L-649/749 engines) and most importantly, the PRT's that gave it the "TurboCompounding" that made the engines famous on both the Connie and the DC-7.
The reason A2A went for the L-049 wasn't to start a "family". It was because it was, for all purposes, the first modern airliner. It was the first pressurized, purpose-built long-range piston airliner ever produced. It paved the way for the DC-6, DC-7, B-377, and the Super Connie that followed it. Most people don't realize the L-049 had completed not only its production run, but most of its service life before the DC-6 had even flown. That's why Lockheed was so far ahead of Douglas and Boeing. They'd been flying the Connie for almost 5 years learning how to do the high-altitude, long range flying in the real world and that meant they could apply those lessons to the Super Constellation and deliver something faster and with longer range than what their competition was able to produce for almost 15 years.
THAT BEING SAID.

I will do something I don't do around here very often. I'll recommend something from another group - specifically, the Manfred Jahn / Team Connie aircraft. While originally for FS2004, they work well in FSX apart from a few minor issues (prop reverse only works from the 2D panel for example).
749 Constellation -
http://www.calclassic.com/connie.htmSuper Constellation -
http://www.calclassic.com/sconnie.htmStarliner -
http://www.calclassic.com/starliner.htm