How is Siege Sixgun compatible with Titan Metroplex?

[Tilarta]

I read a note that some of the SIEGE toys were intended as companion pieces to the earlier released Titans (Metroplex, Trypticon, Fortress Maximus).

I just got Siege Sixgun this week and decided to compare him with the original Sixgun, just to see what I could do with his parts:





Unfortunately, there was not a lot I could do, as most of his parts weren't able to connect with the G1 Metroplex:

This is the only one I could use, the leg guns.



Sockets weren't compatible.
Maybe some creative Shapeways designer could make the adaptors?


Which got me wondering, as the Sixgun SIEGE parts are much smaller then the original G1 parts, how the heck will they be compatible with the increased scale Titan Returns Metroplex?
Where exactly are you meant to connect them?