I would have a shop do it,there are some other factors,like are you going to port it,and if so,are going to run race fuel and what is your elevation you ride in and what compression your wanting.If you have the equipment to shave the head down,what ever your wanting to take off of it,i would go 5 thousands under and sand the other 5 thousands down so you have a smooth surface,weve ran many shaved stock heads and at 420 ft above sea level and head milled down to 40 t dont housands gave use 160 compression,and thats a fine line on running race gas,but we got away with running pump gas without detenation in the cylinder,your best bet would b to buy a cool head with inter changeable dooms for better cooling and then you can already have that when you want to go farther on the mods imo.And milled heads around 40 thousands have a better chance of blowing a head gasket.As far as the timing goes,i really dont see a need for it since its not ported and having t5s are for ported cylinders,so you would get more benifit out of the t5s,T6s are for non ported engines,t5s are for ported engines,i'm sure there will be a few who will chime in on this topic....hope this helps