Based on your statement that you have only one print sequence available, it's risky to gamble on a too-small spacing. I purchased from Angus of Makers Muse a tolerance test model, which allowed me to determine that my minimum spacing is 0.3 mm. It's possible I could fine tune my printer for a smaller spacing, but I'm happy with 0.3 mm for such things.

The minimum spacing is dependent on the layer extrusion factor and you can only be certain how to adjust for that by multiple model tests.

Because of your restrictions, I'd suggest no smaller than 0.4 mm spacing. The disadvantage of wider spacing is if your model has fine threads that are not deeper than 0.4 mm, but it would be foolish to incorporate such detail level in a 3d printed model. They would be excessively weak.