xv 125 virago

hello im in need of some serious help

iv got an xv 125 virago engine and iv managed to brake the cam sprocket on the front cylinder head!! cant seem to find a spare part but am going to go to cmc to get one ordered in.

my main problem is sorting out the timing! the rear cylinder head is set up perfect but the front one is out and i dont know how to sort it can anyone give me a run through on how to sort it out? either by comparing it to the rear cylinder or doing it all from scratch?

cheers for any help .Paul.

ps, iv got my hands on the xvs 125 dragstars barrels and heads ect and they fit perfect on the xv 125 virago engine but the cam timing seems to be different to the virago's just wondered if anyone out there could tell me how to match the dragstars heads to the virago engine/ cdi unit. thats if its a viable option, the rear cylinders exhaust manifold is corroded onto the head so need to see if i can sort it. or if i could get away with just putting the front dragstar cylinder head on the virago engine (the exhaust bolt on the virago head has sheared off and i cant sort it)

thanks again . Paul.