ruffautos

hey guys, i recently drove my 4runner from darwin to victoria towing 3.8ton. everything was going great. once i got down to victoria the air flow sensor decided to pack up. i kept driving it on LPG as it wouldnt run on petrol till the new part arrived, unfortunatly this seems to have set off a chain reaction, after i replaced the air flow it ran good for a hour or so, then started to misfire really bad in drive or reverse an rough idle in neutral. i got a compression test an found cylinder 2 had 98psi an cylinder 6 had 0. being told it was head gaskets i pulled it apart to find that the exhaust valve in cyl 6 had been burnt through an the rest of the valves on the left bank had been tapped out, yet the right bank was completly fine, i also found that when i was lining the timing up that everything lined up except for the right bank cam pully, it was out 2 teeth. what are your thoughts on this?