An OEM HG will hold boost easily to fuel cut....with an upgraded CT26, that is all you really need and it will not require a block deck re-surface. Assuming the block deck is flat of course. I would use ARP hardware (studs preferred) torqued to ARP spec (80 ft/lbs w/ moly) regardless of the HG you choose.
I would still have the head decked and a valve job done with new seals installed. You might as well. Here's some springs that are an upgrade from stock...cheap too:
http://www.mkiiitech.com/forums/viewtopic.php?t=359
You can use the stock retainers...I'd let the machine shop install these. You def want to check the valve shim clearances before you put the head on the block.
If you plan on going with a turbo that can put out 20 psi +, you probably want to go with a MHG. Cometic is fine for most people, unless you are going to the big HP numbers...it's RA spec is the easiest to meet from the rest. If you go this route, realize you will have to do other mods to the motor to support this kind of boost. Planning on doing a re-build on the bottom end may be in order if you have a lot of miles on it...before you up the boost that is.
I'm still working on getting that machine shop number...talked to my buddy, the shop is actually out in Mesa. Cost was ~$450 for deck, valve job, valve assembly....not too bad considering he got it down to an RA of 25
You probably already know this...do not run the car. You likely have coolant in your oil...very bad for bearings. When you get this job done, change the oil/filter before you run it...SuperTech oil/filter from Wal-mart is fine...use 10W-30. Run this oil for 30 min or so and dump it. Change the oil/filter again...this time use a good oil and a Wix or PureOne filter. Take a look at the Oil section for my opinion on oils.
