Converting to electric choke on Holley 750DP

I'm adding a Holley electric choke kit (for internal vacuum) to a 4779-6 750 double pumper w/ mechanical secondaries. While there is an opening in the main block that is fairly deep (1.5 inches), I dont think it has access to vacuum. There is a hole going down through the throttle plate but it does not go all the way up to the vacuum port for the choke piston. Its only about 9/16 deep into the main block. Can/should I drill this out so the ports can connect or is there another source to vacuum I'm not seeing. I've added a few pics to illustrate what I'm talking about.

By the way, the Holley Tech line guy said I MUST to use an external vacuum choke kit. I already bought this one from Ebay and opened it so I can't return it. I'd like make it work if I can.

I would go ahead and drill it, you can always block it off if it doesn't work out.

I'd agree, do make sure to use a gasket ( usually cork) in the recess to seal the port.

You got the wrong hole targeted its one of the lower plane ones and holley makes a a little spacer to bring it up the the housing height.

the one up and left from the one your looking at

I was wondering about that but since I don't have one in my hand I wasn't sure.

Hmm, never seen a spacer But you may be right ?
In the pictures provided it's hard to see which holes line up when the choke is mounted. FWIW: The hole with the brass restriction is the one that needs the manifold vacuum source.

Its been forever so I am going by memory,

yes

Ill look in a minute when I go out to the shop

Ok I 'm going to delete my original post the original poster has the right hole...... the one I referenced is for the vacuum sec. on the main body I checked that hole, that the original poster shows is drilled straight through to the center cavity.

Now I have to figure out what combination takes the spacers.

That's exactly what I needed to know. I wasn't sure if it connected the the lower hole in my second pic to form an L-shaped passage or went straight through to the center. Thanks!

yep sorry for the confusion.

L shaped as straight through would be above the throttle blades giving you "venturi" or ported vacuum versus manifold vacuum which is what is needed for the choke to function properly

Don't forget the gasket ( usually cork) to seal that passage when mounting the assembly

No straight through to the center cavity, between the the two barrels.

that being said you better go straight, or you will end up in the barrel.

You might be right as I was ASSuming and did not have a carb in front of me Thanks for clarifying.