In relation to cracked heads, yes that was a problem here in nz. Second model [& think the cure for the first model head cracker] was a two piece head in-place of three, long ago. Worked for the dealer & local [maybe nz wide] cops used them. Despite their issues they were pretty much ok for the time, 4 valves per cylinder etc. Hell, [letting the cat outa the bag, things you'd rather forget] 'Don't' do what i did once when a customer came in for a wof & had a really rattly cam chain. Thought i'd do the guy a favour & let it go while idling. Yes it jumped teeth & bent valves. Guess what i was doing after work for a few nights. If i recall rite, valve timing is a bit confusing as the cams turn 'backwards'--read the workshop manual & Goodluck.