1967 273 V8 change to 6-pack carbs

I'm not a %100 on this, but 64 was the first year and had the odd ball angle. I do not know about 65 or newer 273's for sure.
The 273 and the 318 share port size. The 340 and the 360 share the larger port size.
You could use it with the smaller ports, but would port match it for better results.