i have found that once the stock carb is properly tuned, it doesn't require any further maintenance for quite a while. i had an '82 air-cooled westfalia and hated every minute of it. non-stop gremlins, like you mentioned, and almost everything on that damn vehicle was impossible to access without removing 6 other things first. worked on a few other vw's and found the same thing so i stay away from them now.
if you are concerned about the bottom end, you could hook an aftermarket oil gauge up to the engine and check the oil pressure on warm idle. i think the FSM says the minimum acceptable level is like 5 psi but that's way too low IMO, and impossible to read with most gauges, so i prefer 10-15 psi which is what i've usually found. low oil pressure on warm idle would indicate worn engine bearings and point to a rebuild in the future.
i personally prefer the stock carb. in cold wet climates, the weber is prone to icing while warming up. not a big deal, it goes away after 5 mins, but it's a hassle. plus i drive slow and don't need the performance aspect of the weber, and i like to keep emissions stuff as intact as possible, and webers cost about $300 up here in canada. way too much for me.
there's lots of useful info in the FAQ on weber's, crucial new-to-you maintenance, how to download the FSM, etc. take a look at it here if you haven't already.
https://tercel4wd.com/forums/viewtopic.php?f=2&t=7442