Convert drum to disc, or no?

I have an original 250 car that now has a 84 302 and the difference isnt noticable but I do plan to convert to discs for easy or brake work and better stopping/safty factor..
I only have spindles for a 74? maverick which is for 10.5 in rotors, but it has to be better then 4 wheel discs...and theres also a few companies that make big brake kits for this spindle since its the same as any mustang spindle

 

correct, smae cars even had finned aluminum drums such as some buicks

 

Doesn't matter if they are air or hydraulic, the principle is the same. Only difference is the medium used to apply the force, air or liquid.
They are larger brakes, but it's also a much larger vehicle.