And fitting a decompression plate between the block and the head will increase you chances of head gasket failure ten fold. I can't understand why people do it.
Then you'll need to get the fuel system totally recalibrated, probably fit bigger valves to get any real benefit from it. I'd leave the decompression plate, and fit either shorter conrods or custom pistons - choose carefully and they aren't that expensive...
Oh, and if you are fitting a supercharger, don't expect much increase in power - perhaps 2o or 30hp at most. The real gain is with low down torque, so perhaps when trying to 'show off' you should quote the peak torque figures. If the kit itself quotes hp figures, DO NOT buy it - the people who 'make' it obviously don't know what they are talking about.