but why must holes be drilled? the engine ran and had acceptable coolant flow without the 3 holes. just cuz there are holes in the gasket shouldn't make any diff. i could see making extra hole in the gasket for a cooling passage already in existence in the block-head. is there even a hole in the head that would flow through to the block hole?

I did a head swap years ago on perfectly good GenV blocks. The prior engine/head combo ran flawless for years. Immediately I started sticking #8 and#6 exhaust valves. I'm lucky I didn't lose a piston with all of the smiley faces I put in them. I tried every FelPro gasket combination and Cometic with the same failure. The only cure was to drill out the back water passages of the intake. The holes in the block help propagate flow throughout the heads and block.

Going with the fel pro 1071 gaskets, look like the best choice
Thanks for all the info.