I believe the consensus view is that 2 widths of top bar are required: a bar in the 32-38 mm range for brood, and around 6 mm wider for honey, although I do know of at least one successful beek who is running brood at sub-32 mm. Having said that, I've been running with 38mm for both brood and honey without problems.
Until you're sure which widths are suitable for your local bees, thin plywood spacers (the same length and height as your bars) could be inserted between bars in the brood area, and removed if the bees show signs of generating burr comb. A simple way of dealing with the honey/brood spacing issue, and to keep your bars inter-changeable, is to simply insert 6 mm spacers between bars in the honey area.