Hi Cam
When I started with my tired 2.0 T (now 2.7RS spec), just getting it to run cleanly was my goal. I started with binning the now obsolete Marelli dizzy and replaced with a machined down 2.7 distributor (as per JWW specs) and sent it to Scorcher Ignitions in Melbourne to have it regraphed for crappy Aussie fuel (10 degrees BTDC), this meant the adjustment groove has NEVER been in the middle. I also added a Crane optical ignition unit and Crane XR700 electronic ignition. I then rebuilt the carbies and put it all together.
I initially had the issues you're describing. I had air getting in at the manifold under the carbs - try cheching this by spraying some Aerostart around the seals while the engine is running. If you get rev fluctuations you'll know you have bad seals. I pulled them all off and used some Hylomar. Solved the problems and allowed me to tune the engine.
The differences with the rebult carbs and particularly the electronic ignition were startling! I suddenly went from a cranky pig to an absolute darling
I recently went through it all again with the build of the 2.7RS spec. This time I encountered the issues you get with completely changing all the internals of the carbs, and like you I suspect, I was living in a "regional" location where sourcing good advice and tools is hard (Toowoomba & Townsville). This time my tuning woes were floats and float valves. I had received one dicky float valve in the kit, which took a while to work out.
I'm sure you know, but I'll stress it again... Float levels are critical! I was using the PMO tool (gold), but presuming "close enough is good enough" the car was a b@stard.... Be anal about gettng the floats perfect!
Oh, this might be relevant, I had a needle with corrosion that I "sharpened up".... yeah I ruined it
So if you have a bent one, change it - it's the same from any weber carbie so a local shop should be able to help.
Hope this helps