I have used adjustable jets on the model 4150/4160 Holleys.  The problem with adjustable jets is getting them initially adjusted so they are actually in the ball park. While too rich can wear the rings and cylinder walls at a faster rate, being too lean can promote some very serious and detrimental engine damage so care must be taken when making those adjustments.  A wide band oxygen sensor would assist greatly in this.  Performing those adjustments by trial and error and simply looking at plug readings or seat of the pants performance would be guess work at best and involve a considerable amount of time and driving.  And where more than one adjustable jet is involved, then having them the same or balanced would be another problem.  If one had a chart that would correlate the number of turns of the adjustable jet to a corresponding area size, then tuning with those could be performed in a more educated manner.

For the multiple setup 94’sand 97’s, I simply use numbered jets. Once a baseline is determined, those numbers can be used on other engine combinations as a starting point.