Carb issue?

Drilling the blades might get you to a satisfactory idle situation..... or not.
It doesn’t really alter the idle circuit capacity.
It just allows more airflow with the blades being in a more correct position.
There’s really only one way to know if it will work in your application.

In the mid-80’s I did several low buck 400 re-ring jobs for guys who wanted a low buck street/strip big block.
These were still low compression when done, and I pretty much always “over cammed” them, since it worked well on the track if you had enough stall and gear.
I used the MP484 cam in a few, which did the job for power, but was a little miserable on the street if the carb wasn’t right.
These motors didn’t make any real power, or flow much air...... so they didn’t need a big carb.
At that time there really weren’t any off the shelf small carbs with 4 corner idle, and the 2 corner idle of the small carbs just didn’t cut it.
My preferred carbs for those was a Holley 4777, 650DP....... but they only had 2 corner idle.
I would modify them to have 4 corner idle, which would really transform how they behaved at idle and low speed operation.

Nowadays, you can buy a 650 with 4 corner idle from a variety of sources.

As for the cam.....”if it were me”, and I was looking to maximize the affect of a cam swap...... I’d go straight to a SFT.