The R-3310 750 Holley will work just fine for you. It should be a dual inlet carb, so you might have to change your fuel line on the inlet side when you add a secondary metering block. The kit shouldn't cost more than $50.00 and it allows you to change jets on the secondaries. That's all it does.
There is also an aftermarket metering plate that uses regular Holley jets, doing the same thing maybe for less.
You don't need to change float bowls for either choice.
If you're REALLY bucks-down you could drill and tap holes into the metering plate and use Holley jets.
1/4-32 is the thread size.
Spend money on springs for the vacuum secondaries, too, for tuning.
R.