This is the list that Mark gave me for mine
I use this company for the head gaskets (need to speak to them though as you dont want the full kit because every other gasket is crap!):
http://cgi.ebay.co.uk/VAUXHALL-OMEGA-SINTRA-SAAB-9000-3-0-V6-HEAD-GASKET-SET_W0Q...
These head bolts (I have had problems with other non-branded bolts!):
http://cgi.ebay.co.uk/HEAD-BOLTS-VAUXHALL-OPEL-CALIBRA-V6-OMEGA-V6-VECTRA-V6_W0Q...
These exhaust manifold gaskets:
http://cgi.ebay.co.uk/Vauxhall-V6-EXHAUST-MANIFOLD-GASKET-CALIBRA-VECTRA_W0QQite...
The cam belt kit from buypartsby (sutton auto factors) will do the job (would need to keep the old backing plate but the rest is the same).
I have had good success in re-using the cam seals (dont take them off the cams) but find the non-gen ones leak....
Then for genuine bits you will need:
4 Dowty washers for coolant bridge.
Cam cover gasket set.
coolant transfer pipe O ring.
2 front pipe to manifold gaskets.
Black cam cover sealent
Grey goo(for oil cooler plate)
Green sealent (for front bearing caps)
I also re-seal the oil cooler when the heads are off as a matter of course (coz its easy to do!) so you would also need 4 of the metal washers for the cooler to pipe conenctions.
Then its oil and filter.