Why not all of the above? Perhaps in the beginning when you are just trying to get your car running, anything will do. Then you might begin to see that floats, gaskets, fuel valves, banjo bolt filters, needles, nozzles, dog bones, accelerator cable, linkages, butterfly plates, and vacuum leaks mean something..... Time to upgrade like you tend to do anywhere else on a classic. As one person stated, classic cars tend to be over maintained vs the grocery getter.... You need tools to do that, so, a Unisyn, Colortune, digital caliper and credit card are what you need for carbs, LOL.If you want absolute accuracy, get a Gunson Colortune.
Anyway to me that's part of the learning process for this crazy hobby.
Linda