Confused on brakes for Western Chassis drop spindles

[jjlett69]

Have a question(s) that probably has been addressed a million times and I have searched and read old posts but still confused.
I have Western 67-70 2.5 drop spindles on my 69 C10 with 15" wheels, and the only reason I know this is that I am currently running 69 tie rods. (ordered new and measured against old ones). I currently have 1" rotors 5 on 5 bolt pattern (measured them) with 73-87 calipers (PN GM 5474177/5474176). I am currently replacing rotors and calipers but would like to go with the 1.25" rotor and caliper. Can I order bearings/rotors and calipers for a 73-87 truck and will they work with my spindles? Or do I have to stay with 1" rotors and calipers from lets say a 81-87 V6 truck? Basically is the only difference between the years of spindles the tie rod hole size taper? Thank you all for your time and wisdom!