I'm no expert but if you were to add 1/2 stop (160 + 40 ) you'd be at 9.5 min's if 8min works when rating @ 160.

FWIW:
I like triX in d76 or microdol -- I don't know what my times are, but I dilute 3parts h20 to 1part stock for both -- habit more than scientific -- I feel I get a smoother neg.