Good point! Jetting Holleys is easy, but dumping all that fuel is a PITA, especially on a hot manifold. I used to keep several sets of bowl and metering block gaskets on hand when tuning because with the old cork ones, you never knew when they would let go....
I guess once you have it all together most of the tuning is external, but the power valve would be annoying to me to have to drain and knock off bowls every time until you got it right.
