500ml water + 50-60g lye should give a high enough ph (12.5+) to basify the acidic water solution.
It doesn't need to be at 13.5 to freebase all the DMT.
I don't know about calculating moles, but I just use cyb's max ion tek and it works fine.
A ph meter or papers will make it a lot easier if you are aiming for a specific ph.
There are teks for all different amounts as well, if you are not a chemistry buff.
https://wiki.dmt-nexus.me/Category:Extraction_TekSwim should swim a "machine" swim for swimming swim.
Swim through the teks and do some more swimsearch and you will be fine.
Taken from the FAQ -
https://wiki.dmt-nexus.me/FAQWhich ratio of MHRB:Lye:Water is the best?
For STBs, 1g MHRB:1g Lye:15ml Water is generally accepted as a good ratio. People have had success with significantly less water, but 15ml per g bark is a recommended amount because less than that might make the whole mixture too thick and it can make the separation of the solvent more difficult. Also, one actually needs much less lye but this amount of lye helps prevent emulsions forming as well helps break down the plant material so that dmt is more exposed to the water.
Alternatively, one can just add enough lye for the solution to turn completely black, and go ahead and extract. If emulsions form, add more lye. One does not need to worry about over-basifying, there's no such thing. Excess lye will stay behind in the water layer once you separate the solvent in any case.
Welcome to the Nexus, good luck!