Suitable potting mix for Heliamphora

[SoLongFairWell]

I'm just about to get a new Heliamphora to try again. The heterodoxa x ionasii hybrid which I've been holding out for. I shall be growing on a windowsill on the tray method (shallow water) with top watering every couple of days into the pitchers.

Anyway I'm trying to find a suitable mix to pot it in.

D'Amato suggests two possible mixes whilst stating the plants are reasonably easy going as long as it's wet and well drained. These are:

3 parts Sphagnum

1 part lava rock

1 part perlite

or

half peat

then equal combination of:

lava rock

pumice

perlite

fine bark

Now of course we don't have lava rock or pumice (most of us) but I do have the tesco dust free cat litter that I use for mexican pings. Can I use that in the place of lava rock and pumice?

That would mean my own 2 possible recipes would be:

Mix A

3 parts sphagnum (dead)

1 part cat litter

1 part perlite

or

Mix B

half peat

then equal combination of:

perlite

cat litter

fine bark

So 2 questions are; can I use the cat litter for Heli's? And which of my proposed mixes (A or B) do you think would be best?