Thats the truth Phil!!!, a phazer with a pipe and a bender cold air kit would run great, lots of power, reliable. As soon as you ported the cylinders and reeds(really adding airflow) the stock butterfly carbs would destroy the engine every time in the mid range, no matter what, I drilled out the passages in the carbs, used 110 pilot jets, nothing would prevent the mid range slow burndown. Its the way the carbs are designed to pull fuel.(or lack of!!)
We eventually used a set of exciter slide carbs and the sled woke up even more power and we never replaced another piston in it again, they actually can be quite powerfull little motors when done up, but if you mod one, just change the carbs or youll drive yourself broke and nuts all at the same time....LOL!!! ahh the good ol days of the phazers............