Gauge ? *plz help*

I knitted up a gauge using bulky wool.
Size 6-7 5st=1"
Size 8 4st=1"

I am making longies [or pants like these] and this is my first time using bulky. I usually use 6’s for the waist [2x2 rib] and then go to 8’s for the rest.
[B] My question: when I use the 6’s should I CO for 5 st per inch and then decrease when I switch to the 8’s?[/B]

Example: 165=80+3 so I would do 83 st’s for the rib and then decrease to 67 st [164=64+3=67] for the body?

please help me.

I would think that if the original pattern works out with the two sized needles, and you reduce the number of stitches for the size 6 needles, that that would be proportionate for the size 8 as well.

I think I’d reduce the number of stitches and then just switch to the 8’s and stay in pattern.

Yes

Thank you both.