stock flow rate is 36# (some sources say 33#)
if you're using DHP, injector flow rate is msec / g. So you need to shave the time the injector is open.
if using HPT I think the IFR table is g/msec so you need to increase the flow rate

Multiply stock IFR by 36/80 = .45 (DHP) or 80/36 = 2.22 (HPT)
if your IFR for 42.5# is already dialed in, then multiply your current IFR table by 42.5/80 = .531 or 80/42.5 = 1.88 for HPT

then scan and dial in the MAF table again