Which soil mix ingredient is a should and which a should not for potting up a Pseudophoenix?

[Phoenikakias]

I have been growing from a two strap leaf seedling this sargentii sub. navassana.  A couple of times got sick and almost perished, but after a persistent treatment with fungicides has finally set off. But it needs currently a new bigger pot, as the used liner looks to small for the size of the plant. I would hate though to go again through same health issues with it. So I have to think over the most suitable soil mix ingredients to this purpose. Readily available are pumice, leca, lava, perlite, gravel, pine bark beside the traditional soil ingredients peat and coir. I would like therefore to read your own recommendation regarding those ingredients and preferably the percentage of each in the soil mix. Thanks to all of you!