T Thanks OCD....been offered them for £110 the pair brand new from a guy who didn't put them on his bike as he sold bike prior to use.
I used to check tyre dates and never fitted anything over 2yrs old, until I bought the 04 track bike, the chap I bought it off said he hadn't used it for a few years ,never got to check the dates on the tyre but they looked in good nick so did 3 track days on them with no problems. when I replaced them I clocked the date and they where 8yrs old !!!! so in answer to your question is IMHO i'd go for them, i'm sure someone will come up with a valid reason ( other than my ramblings) as to why you should or shouldn't use them
Generally speaking a tyre up to 5 years not a problem, 5 to 10 years should be checked periodically for irregular shape, bulges etc. After 10 years bin it. Having said that it's worth checking the manufacturers advice.