RE: Custom chassis plate
If you had a decent CAD program couldn't you just scan a chassis plate and import it to get the dimensions? Of course you could always sit down with a chassis, a good set of claipers, and a pencil and paper and just do the grunt work. If you have access to a CNC machine you could use it with a tooling ball mounted in the spindle. There's so many different ways to get what you want and it wouldn't take that much time, why not do it one night instead of watching TV or reading message boards?