Fitting a stock tightly and properly is frankly one of the most frustrating and complex jobs, I have ever tried to do. I'll admit I am a failure, so I went an easier way.
Do you want to be authentic? If so then yes wood. Assuming the forewood you have is original and serial number stamped, I would suggest if you can afford it, buy a spare forewood and practice on that first would be my suggestion. The one below is a SA contract wood replacement stock with sucky colour and bad machining converted to a mk2 config from mk1. So my original is still as is right now.
Personally I replace work draws with blocks of brass that can be packed to get the rifle to sit "right" but Aluminium will do fine, just dont use steel screws to hold them in place!!!!
Though Peter will have an epi Im sure...
;]