I wouldn't be replacing any valves, check they are all straight and that they aren't sinking (being pulled) into the head, if they are ok and the valve seats look in good shape then just change the valve springs, the only other head work to be done is just time consuming and delicate work. SLOWLY and only a little at a time (as it's hard to put metal back) open up the exhaust ports to match your exhaust and the same with the inlet's and your carb manifolds, (The carb manifolds are easier to work than the head (as a general rule).
The crucial bit in any engine is getting the deck height right, once the short block is assembled, trial fit the pistons and barrels and measure things (this is were is starts getting complicated) then measure the CC capacity of the heads, adjust the heads to suit and create a nice 8.5 to 1 compression ratio, Higher the ratio the higher strung the engine is, and too low and then engine will perform really badly.
I buy expensive parts so prefer not to do alot of this myself and get a PROPER and EXPERIENCED engine builder to do it for me! If your serious about doing it yourself find a freindly machine shop and read some of the books available on building higher performance vw engines. Also seek as much advice as you can, most vw shops are freindly enough to give out some info, but remember it is their livelyhood so won't be teaching you every trick of the trade
The crucial bit in any engine is getting the deck height right, once the short block is assembled, trial fit the pistons and barrels and measure things (this is were is starts getting complicated) then measure the CC capacity of the heads, adjust the heads to suit and create a nice 8.5 to 1 compression ratio, Higher the ratio the higher strung the engine is, and too low and then engine will perform really badly.
I buy expensive parts so prefer not to do alot of this myself and get a PROPER and EXPERIENCED engine builder to do it for me! If your serious about doing it yourself find a freindly machine shop and read some of the books available on building higher performance vw engines. Also seek as much advice as you can, most vw shops are freindly enough to give out some info, but remember it is their livelyhood so won't be teaching you every trick of the trade