So were actually wayyyy beyond the SAR of sasha's day. Now we don't always make new drugs based off existing structures. With the advent of mapping out actual receptor structures, ai, and molecular scaffolding, we predict new drugs based off receptor shape itself. We can predict new structures that we know will likely interact with the receptor how we want, and come up with structures that don't resemble typical known structures.
Tryptamines themselves yeah there's a lot, but there is a finite number. You should check out this patent by Wallach, he's at the forefront of novel tryptamines currently IMO.
Here is the link to his patent, not sure why i can't see full text, but it is EXTENSIVE, maybe more so than Tihkal..
I believe theres over 200 fluorinated tryptamines he made.
If anyone deserves IP/patent, it's wallach.