Sometimes there is a little wiggle room between the top and base, so you might try to unbolt it and see how much movement there is before you start grinding. It would be worth a look to take the top off and set the intake on the heads to see how closely the ports match up.

As far as tunnel ram carbs for a race car, I like the 4224s (660 center squirters). They need their idle circuit leaned out, but that can be fixed with a piece of wire. For wide open use, they are hard to beat, that is why they are also popular with the boat boys. Grumpy was a little partial to them also. You can set them end to end and still get the bowls off, so the linkage is also straight forward.