Actually I was thinking that you could build a fairly credible necromech out of a Body human model, some green stuff (okay, lots of green stuff) and various spares.
As for the titan gigamek, it could be just about any size you want it to be (my Mishima source book is 7,000+ miles away so I can't be exact). I remember they were big, but not necessarily so big that you have to outsource their construction to a resin firm or three then decided there is more money if you do it yourself and revoke their contract making their models that were based your sculpts out of date which you then resculpt at your own resin outfitters that just happens through some liscening loophole to take the name of one of the companies that you previously liscensed to then make similar if not the same type of models and charge five time more for them but big enough that you could probably fit them on a table (maybe 12-18 inches tall).

Yes they would fit into the Bauhaus Grizzly category both in points and playablility, and tournament play is nix but for having something cool on your table top to impress your friends they aren't completely outside the realm of possibility. Plus I'm sure some of you have been eyeing those Gundam models or old Shogun Warriors in your closets gathering dust...