Like olkskol said, you should try to keep the proportions correct by volume. Too much peat will make the mix mucky and you risk going anaerobic or running into watering problems. You also run the risk of being nutrient poor which Is not great either. How large of a bed are you doing? There is a recent “shaping fire” podcast with a guy who runs a notill facility that had some great ideas that I wish I had heard when I was setting up. Worth a listen but basically he was saying that the beds should have a mineral rich layer in the bottom strata of the bed and that the material should be more organically rich in the top of the planter. This is both for drainage and also to replicate the strata found in nature which plants have evolved to thrive in. I guess instead of top dressing mineralization he thinks it best that the minerals are banked below so they the plants have access through natural soil cycling. An interesting theory and one that has apparently worked for their facility.
Look forward to seeing your work as you go forward.