I never thought of doing something like that, but it would definitly take buckets of time trying to file down and add up edges, plus the shape of certain bits to!
What would you think of using for the bone jaw?
The bio could probably be altered into a berserker by changing the colour and adding a jaw bone but probably wouldn't be that accurate as there is only so much you can do on a thin PVC plate. To add the jaw bone you looking at using resin i reckon and adding that to the bio may cause it to distort out of shape so that will need to be reinforce somehow.
As for the latex mask - I have no idea but it would definently take alot of time to adjust as rubies is AVP based and berserker is a different concept altogether.