Hi if its failed a sniff test its academic the gasket is leaking, I personally would do the same as the first garage if you take in to account that the head will most likely need a skim to correct any surface defects, then the valve seats would need to be lapped in, the timing chain is worth doing as even at 60k its probably stretched and the guides will be worn, factor in possible bore wear and you have the potential for a catastrophic wallet failure, from memory these engines were not good from new and if driven hard don't generally take to much action, you also mentioned improvements, one of them was not mapping was it? Steve.