SWIM does a special LSA specific double A/B extraction on the seeds. That effectively gets rid of the toxins. If you can extract DMT, you can extract LSA, but it’s a slightly different process.

You extract with boiling acetone. Evaporate that, then dissolve in water and you do 8 defats with DCM to get rid of most of the toxins.

You then freebase at pH 9 with sodium carbonate. Then during the freebase stage you cannot do any water washes or you’ll lose product (just like with mescaline). You extract 5 times with DCM. Then distill off most of the DCM, until down to about 25 ml.

Then extract with dilute hydrochloric acid or vinegar. Then defat again about 3 times with DCM.

Then freebase at pH 9 and extract with DCM 5 times. Then distill off most of the DCM, until down to about 25 ml and let the rest evaporate to get fairly pure freebase LSA and some other alkaloids.

At that point it's a good idea to salt it with hydrochloric acid and let it all evaporate. Then make a 50:50 glycerin:water tincture out of the alkaloids, and add vitamin C to it to preserve the alkaloids. Such a product produces no stomach upset at all (unless you OD on it).