Rats, beat me to posting by THAT much! ;) I was holding off until better images became available, but here's some more info on this figure:
This bad boy, unveiled in magazine scans a few days ago, is indeed based on the preliminary design for the Heisei Mechagodzilla to be featured in the 1993 feature film Godzilla vs Mechagodzilla II. Designed by Shinji Nishikawa (who is also supervising the creation of this figure), this original take on the iconic mech was far more akin to the design aesthetics of the Showa Mechagodzilla, and would have featured the ability to split into two distinct halves to fight as a duo of mechas, an ability that was ultimately dropped and given to Moguera in the following year's Godzilla vs Spacegodzilla. This ability can be seen in the concept art below:

Not strictly an SHMA figure, this prototype also falls under the newly christened Tamashii Mix line of figures. There is no confirmed release or corresponding promo pictures as of yet. A release date and price, therefore, have yet to be announced.
Look for more info coming your way soon in the SHMA Info and Updates Thread right here on Scified!