You mentioned earlier that you had seen the specs for the Konami arcade pad design. Could you please point out the website that you found blueprints/pics of the pad with electrical specs and all?
Perhaps you could add an adjustible height option for the pad with extendable leg contraptions of some sort And, also, for the shock absorbers I was ...
You may want to consider adding the bar as a side accessory that you can purchase seperately and just snap on -- it would solve the problem of having to make different versions of the pad.