bigger brakes on maual system

[usa-69z]

Hi , can you guide me to the right disc/calipers for my application please... My car is a 69 camaro ,, stock disc up front / drum rear setup.. I have a 7/8 wilwood master with NO booster , maual brakes with proportioning valve. Im wanting to upgrade my manual system and run larger discs (18inch rims) and calipers up front only. so what would i get best response from as a disc/caliper kit to suit the manual 7/8 master system?
I seeost bigger brake kits run a taller spindle? any reason for this? id like a bolt on kit .. does a taller spindle change any height adjustments i have made now?
there are so many kits available , it gets confusing

Gav