If you have access to rockauto.com, they show to have boosters for both OE '86 Civic and '85 Prelude.
I was able to purchase the 85 Prelude MC from RockAuto, but since I couldn't find the 85 carb prelude booster on that site, I ended up ordering it from Autozone new.
I will try that 85 base prelude Booster setup on my daily red 86 Civic Si. I will try the AP1 S2K setup on the white one