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Most taxi heads make the best cores for porting as the ones around here are never cold started and run on 15W40 diesel fleet oil. The heads are always spotless other than the intake ports and all tolerances are still within OEM specs. If they could get the valve seals to last that long the intake ports would be spotless too.
Now a F150 head seems to only last 100,000-200,000 miles and usually the cam bores are damaged by that point. Its all in how it is used and maintained.
105k...lol i only ever payed attention to mine....ive put mileage on the new motor but hasnt made it that far yet, ill let you know if it breaks 100k hahaha