Not ran this car without the servo, but my old mini was servo less.....brakes weren't as good though (but that was because i was a student and skint!)
To be honest, try without and see how you get on, you could always fit one at a later date simple and cheap enough. They come out real easy - or maybe thats just because i've done it a few times so threads are all nice and greased.
I would like to remove mine to make engine In and Outs easier....but reluctant to alter the brake setup just yet (saving that for the full rebuild)
As for the steel plates....I just went down my local metal dealers and got a load of 3mm offcuts thay had lying around. Got a load for not alot of cash (I always put on the skint student routine even though i'm in my 30's!!!) and they cut real easy with a grinder and thin cutting discs - easier getting them laser cut to size mind you!!!!!