Wyeast switched from production date to best by date recently. The rule of thumb that best by is 6 months from production isn't correct. From Wyeast - " This date guarantees our products for a minimum of 6 months." A few months ago I bought some Wyeast online. The best by date was 4/14/21 which would mean a production date of 10/14/20, using the 6 month rule. However my order shipped from the home brew shop on 10/12/20 which would mean the packaged date of the yeast was more than 6 months, or they packaged the yeast while it was on the FedEx truck. My guess as to why Wyeast changed date formats, so they could sell yeast that is now older than 6 months...which makes it harder to guesstimate viability.
For the OP, I'd suggest using 1m/ml/p pitch rate for a high gravity beer like that. So for 5 gallons of 1.082 beer, you'd need about 375B cells, which is close to half of what you have. If you can, make a 2.5L starter with both packages. That will give you plenty of cells. If you can't make a starter, I'd highly recommend getting more packs or you will be under pitching. Even for a normal gravity beer, 2 packs are barely enough.