FORDS lower limit is pathetic, it is perfectly useable way below this limit, just ford won't get a new head sale out of it!!
12 thou and then no good, what a laugh, what a load of crap.
It is up to you wether you take the opportunity to check the valves/guides or not, as they are VERY prone to wear, as it will not be me doing the work or having the additional expense/hassle, persoanlly I don't care, as they say you can lead a horse to water but can't make it drink, if you want to chance it go ahead.
tabetha