If you swing the driver 100 mph, then you should likely be in a stiff flex anyway. 155-160 yards for a traditionally lofted 8 iron is pretty damn good. While you likely won't see a gain in distance, the flight will be more consistent and flighted lower. If you REALLY wanna hit it further (i don't know why you would, other than to feel tougher?), just get some irons with jacked lofts. Your 7 iron is now magically an 8 iron.

Any suggestions from the peanut gallery wouldn’t be much more than a guess. We don’t see your trajectory or tempo.

You can add lead tape to get the swing weight up to D3/D4. A lighter shaft may not change the swing weight that much and the shaft at your speed may decrease your accuracy. There is no standard for shaft flex, and bend points are a more important factor than flex in switching shaft lines.

At some point you’ll need a shop that can pull your shafts anyway. One may have shaft options you can try. Another choice is to pay for a T100/T100s fitting, compare the shafts and hope the AP2s will show the same result. With new grips and ferrules this will likely be in the range of US $400 for 7 clubs. The clubs are 5 years old. Value becomes the issue. If you guess wrong, your performance could suffer. Would getting fit through multiple shafts for new irons to match your swing be a better investment?