Background. Truck is a 1980 K20 with factory auto and vacuum brakes.
Over the past two years:
Found a member selling a hydrooboost from an 86 K30 Auto with hydro brakes and bought it.
Found another member selling a hydro clutch and brake pedal assembly from and auto truck (and told me it had the hole already for the hydro setup) and bought that.
My immediate goal is to swap to hydro brakes with the auto as I can't pull my valve covers (built 496 on solid motor plates front and rear). I have to unbolt the booster to get to the valves to adjust them (major PITA).
Future goal is to swap to a manual trans.
With the parts I acquired I was going to install clutch pedal/brake pedal hanger assembly behind the dash, convert to hydroboost, and run the auto hydroboost pedal for now. When I swap to manual, I was going to install clutch and manual hydro pedal in (should be easy at that point).
I'm running into a few issues. The simplest is I don't have the brake light switch bracket that mounts to the pedal (have several for auto), so if someone has that I would like to buy it (see picture with circle).
Next issue is that I can run the auto pedal for now (it has the 2.875" pin spacing as stated in the hydroboost swap post). https://ck5.com/forums/threads/illustrated-hydroboost-swap.306221/
My question is the manual pedal that I was planning to use with the "two holes" is different. From my measuring, it looks as if the pin to center pivot distance is approximately 2.60. I'm assuming that is no good and I still need to find the right pedal (or cut my auto one down)?
Anyone know what that hole is for?

Over the past two years:
Found a member selling a hydrooboost from an 86 K30 Auto with hydro brakes and bought it.
Found another member selling a hydro clutch and brake pedal assembly from and auto truck (and told me it had the hole already for the hydro setup) and bought that.
My immediate goal is to swap to hydro brakes with the auto as I can't pull my valve covers (built 496 on solid motor plates front and rear). I have to unbolt the booster to get to the valves to adjust them (major PITA).
Future goal is to swap to a manual trans.
With the parts I acquired I was going to install clutch pedal/brake pedal hanger assembly behind the dash, convert to hydroboost, and run the auto hydroboost pedal for now. When I swap to manual, I was going to install clutch and manual hydro pedal in (should be easy at that point).
I'm running into a few issues. The simplest is I don't have the brake light switch bracket that mounts to the pedal (have several for auto), so if someone has that I would like to buy it (see picture with circle).
Next issue is that I can run the auto pedal for now (it has the 2.875" pin spacing as stated in the hydroboost swap post). https://ck5.com/forums/threads/illustrated-hydroboost-swap.306221/
My question is the manual pedal that I was planning to use with the "two holes" is different. From my measuring, it looks as if the pin to center pivot distance is approximately 2.60. I'm assuming that is no good and I still need to find the right pedal (or cut my auto one down)?
Anyone know what that hole is for?