I would breadboard (or stripboard) the circuit first just to make sure it works before you start losing your head about it. If you go stripboard, be sure to buy the IC chip sockets so you dont have to have it permanent! Feel free to share pics of that if you have any issues with getting it up and running. Do you have a modular power supply yet? i would start there first, so you can test modules and actually have something working!
Here is a thread for the Frequency Central Microbus Power supply. I include Sam’s vid on the case, and a link to the builder’s livestream on his patreon. It also has the build doc and a BOM which includes links to tayda so you can easily get the parts you need!
The AS3340 should be a pin for pin drop-in replacement. Its been said that there are some quirky stuff to keep in mind with resistor values and the square output, but its all i use, and yeah they work fine.
See this thread for a discussion about the weird stuff.
I got mine from Electric Druid.
As far as common components, i made a post in the Cheap Components Thread a while back that might prove useful:
You definitely want to buy op amps. They are used a bunch in many different types of projects.