Yes bud, you have to get second gear pinned. GS boxes are good for very low 8's. I had a turbo suzuki running 8.1's @ 166+and second gearpinning was the only mod to the box, apart from an extra spring on the shift drum.
They are bullet proof virtually to 8.0's anything below and I reckon they would still hold up. If the job is done properly, you will not have a problem with the gearbox.
I know of people shearing the pin, but replace pin and it is as right as rain to go again.