How to treat gaps in 6" pine boards

We are currently renovating a 100+ year old queenslander and are preparing the 6" pine floor boards for sealing. We have had the floors sanded and had the dirt accumulation between the boards cleaned & vacuumed out, we are now left with gaps ranging from 0.5mm to +5mm. I am looking for suitable suggestions on how to fill the gaps, I have doen some test spots with both pine timber filler - which is way to light, and have tried builders bog which is too grey. Any suggestions would be appreciated.


More...