im doing an engine rebuild/upgrade on my a4 ive got

frankenturbo F4L kit
225 tt injectors
integrated engineering rods

my head has been beaten up in cylinder 3 so im looking to upgrade it to a large port head, either an AEB passat or AGU golf head rather than replace with a stock one.
i would just like to know what sort of work needs to go into this, what parts needed to do this conversion?
is this worth doing what sort of power gains could i get over stock head running my K04-015

im a noob to this im sure this has all been covered before if someone could point me in the right direction would be much appreciated