I do like the snail for most jobs, but the Uni-syn is better in a 72 with stock carbs (no upper hatch to peek at the snail through), the Uni-syn is perfect in that application.
Try to find an old real one, the modern ones are sort of OK but they are made in China (need I say more?), the only issue some of the late 70's/80's versions develop is the sight tube is plastic instead of glass and sometimes warps so the bead sticks in it. Swap meets (not just VW ones) and Craigslist are where you need to look, there's hundreds in dear old recently deceased Dad's basement that his non mechanical kids want gone.