I use the beergas, same blend, for guinness and homebrew. The same things apply here, how long is your beer line, and what is the ID? You want a minimum of 5', 3/16"ID hose, preferably 8'. Your PSI sounds about right, 25 to 30, at around 36-38˚.
Make sure the restrictor plate, flow straightener and O ring are correct in the spout. Also make sure you pull the tap handle all the way down, rather than partly open. If it's partly open you cause foam.
Dispensing goes like this:
Open faucet all the way towards you, holding the glass at an angle close to the faucet, to avoid excessive turbulence. Fill 2/3 to 3/4 of the glass, let it settle foe a minute or two. You should see the cascading bubbles, just like a guinness, but it clears up quickly.
Finish filling the glass by pushing the faucet, that will add the last bit of creamy head.
I'm off to brew an oatmeal stout right now so here is some good info.
Micromatic article and parts breakdown
Pouring A Perfect Glass of Beer