If they are a mfr date of 21st and 23rd week of 2016 then they are well past their prime. Most performance tires have a 4 year shelf life where the compounds become stale after that point. (Technically compounds oxidize right out of the mold). Just a FYI.
I’m sure they can be used in a street driving setting but using them for their intended purpose might lead to disappointment.
Im in the SF Bay Area and was considering swinging by wherever you are after a SoCal track day but $700 for 6 year old tires seems a little steep.
As a side note the tires were purchased by myself originally some time ago and have been kept indoors in a climate controlled garage the entire time. Thanks.