Extreme
API
Mocom
Scoobyclinic
Zen
Graham Goode
TSL
All of the above plus a good few others have said not to do just the head gasket, although im sure your right and it can be done cheap i would like the peace of mind plus like i say a few bits internally like pistons, conrods, crank etc will more than likely be uprated in preparation for alot more power.
Tony