Getting ready to clean carbs up and just notice the front of the carbs have been machined at angle to butter fly. I have never seen this done on SU carbs.

Has anyone else seen this done?

I'm guessing it doesn't do much one way or the other. Doesn't make things much better, but pretty sure it wouldn't make things worse.

Did they do the same thing on the exit end at the butterfly?

No. not machined on the exit

I'm thinking a PO was running a velocity stack snout or was matching the hole to the back of a non-stock air cleaner or something.

The PO had fun with the air cleaner. He cut long slots all along the top and bottom of it. Thats what I was thinking the stacks but non where on the car when I saved out of a farm field.