660 center squirter

I recently aquired a 660 center squirter and installed it on my truck (which is in desperate need of a bigger carb).
Now that I have done this, the truck will not idle below 2000 RPM.

I had my boss look at this setup and he noticed that the butterfies were drilled. He also stated that this meant the carb was probably run on a tunnel ram/dual quad setup with a radical cam sometime in the past.

Is this a possible reason as to why the carb is idling up? It seems that this would cause a vacuum leak on the primaries and secondaries.

If this is it, is there any way to plug these holes? The truck runs great with the carb on it, but it just idles too high.

How big are those holes? usually a 1/8" hole is enough to allow the idle circuit to function. That shouldn't make your engine run at 2000 rpm. Are the secondaries open a bit?
A steady hand and a soldering iron should fill them without damaging anything else. Just be sure the solder bonds good and won't fall out!