It's an interesting study. The 2H was ubiquitous in the overseas market however the 12HT was a relatively short run (from my understanding). Why they did some reengineering to make the 12HT is worth considering. Toyota's engineering motto seems to be to over engineer and under power which is...
Yikes! My 78 had a weber with a fuel regulator on in when I bought it. It ran ok but I wanted to use the stock air cleaner so I bought a city racer carb and swapped it out. Runs great now.