As this post may have been aimed at me, I feel I should respond: but in doing so, I plead ignorance because I have never resealed an HW90 ... I tend to collect trivial information 'just in case'. So... as I cannot rule on 70 or 90, my advice is to go with what the more informed people say .. maybe 90.
Mind you, if I was piushed into a corner and only had 70 in stock, I would be sorely tempted to try them, enen if it meant I had to get 90 shore later. But that is just me ...
Cheers, Phil