Thoughts on Valve size?

I know it's not "best practice", but since I'll get is square decked anyway, I'll probably get some extra taken off. And I have a family member with the gear to shave the heads down too.
I lot more faffing about than just buying better slugs. But it's more about making use of what I've got. I have way too many cars, and projects in the works to be throwing lots of money at it.