That was a good idea to take it back to the guy who rebuilt the carb...glad it worked out for you.
For fuel filter, I always go Toyota (OEM).
That pipe that curves up and out through the body of the insulator is a vac pipe. If there are cracks in the body of the insulator around that pipe, then it will be a significant source for a vac leak. If you wiggle that pipe a bit (don't put too much pressure on it) and it moves about within the insulator body, then you probably need a new insulator (also still available new from Toyota ~US$150).
When dettatching/attaching that hose that connects to that vac pipe, be mindful not to put too much pressure on the pipe, otherwise you might crack the insulator material around it (if the insulator is old and has seen a lot of heat).
Your US$50 used insulator should be good as long as the top and bottom surfaces are flat (not warped) and the pipe is still secure in the insulator body with no cracks.
When reinstalling the insulator onto the top of the intake manifold (and underneath the carb), dip your finger in some clean motor oil and spread it over the surfaces on the top and bottom of the insulator gasket where it makes contact with the intake manifold and bottom of carb. This will help it keep a seal, but also make it easier to remove next time. If you didn't do this on this last re-installation, don't worry about it too much...not too big of a deal...
If you still have issues passing smog, post back up on MUD and consider installing both a vac gauge (to read manifold vac) and AFR gauge (to measure air/fuel ratio in the exhaust stream)...search here in the '60s section' on MUD.
Here is a recent thread about the AFR gauge:
https://forum.ih8mud.com/threads/getting-my-butt-kicked-trying-to-ca-smog-my-60.788392/
https://forum.ih8mud.com/threads/air-fuel-mix-gauge-opinions.483391/
https://forum.ih8mud.com/threads/passing-kalif-smog-with-an-air-fuel-mix-meter.838628/#post-9591042