No 32 Scope fitting with mismatched brackets and pads.

I am having trouble swapping one scope for another onto an existing bracket and fitting one bracket for another onto existing pads, finding the need for packing in some instances where the brackets are not precisely manufactured.
What is the best way to approach fitting mismatched No32 scopes/brackets/pads?.
Once the holes at the rear pad are drilled, I assume the screws will always pull the pad back into the same position, so can the pad be "adjusted" somehow, and similarly, can the front pad be "adjusted" to correct lateral alignement without removing, skimming or packing and refitting?.
If so which surfaces should be "adjusted"?.
I assume it would be wrong to "adjust" the bracket as has happened to one that I have.

You are asking the proverbial '.....my car won't start' question without enough info on which to base any soirt of coherent reply

Is it an original scopeless rifle without a bracket? Are you startring from scratch? what is original out of what you've got? Is the telescope centred?