Looking pretty awesome- do you have any pictures of the steel gears?
Chances are they'd either be the real/official UltraMaxxed Ti gears set (maybe with the brass or bronze idler gear ), but if they are actually steel ( easy to test with a magnet ) then they are a copy which appeared on ebay some years back and promptly vanished again soon after. Anything is preferable to the plastic gears though
I had the GorillaMaxx motor mount too at one point, but I found it flexed too much even with the motor mounted low / to one side- really needed to be more like 5mm thick instead of 3mm...