4cyl sohc head gasket

[vk6fun]

hi

my son's car needs a new head gasket (yeah, and probly more...)
its a 230te body but the engine has been replaced sometime last century.
so i took off the rocker box cover. lots of mud!
i also took off the thermostat housing and i notice tstat seems to be stuck wide open.... hmmm.
this donk has a single row timing chain and psteering pump on the front end of the camshaft.
i,m guessing the best strategy is to pull the head, exh mani and injection manifold off in one unit.
can anyone help me with the timing chain and how to get it off (erm, and back on...)?
i see the head bolts easily accessible either side of the camshaft but peering down the timing tunnel i can see some big allen screws. i think there are three.
i'm a newbie when it comes to merc engines but i'm looking forward to the experience btw what a GREAT website. took a bit of finding tho...

cheers from peter vk6fun beckenham western australia