You could always set the dampers a little harder to minimise rubbing. Worst case scenario you'll need to do a bit of rolling. Have you got an adjustable pan hard rod?
The rears only do around 10-15% of the braking. The drums will work just as well as the discs on braking. But you'll have a far better handbrake as a result lol.
Drums for the handbrake run rings round the calipers. My N/A used to be left anywhere on the handbrake alone. My glanza I wouldn't trust even in gear lol.