unfortunately mine is on the horizontal so its engine out for me- wierd thing is i never noticed any extra rattles or bangs i was just giving it a clean-the cam doesnt look as bad yours cy but i would feel happier with a new one that isnt worn- i have got spare bottom end. barrels and pistons but no spare heads
belts were done 4000 miles ago-i'll have to wait until next week before i get chance to get the head off to investigate further