A 4" lens would handle that with no problem.
Printable View
I ended up buying a 2.5" lens. The Universal Laser lens selection article says it has a tolerance of .15" I focused it, then brought the lens about .085 closer. In theory that would give the the .15-.16" variance I needed. Based on a suggestion from the Universal technician, I did boost the power a little higher than normal. It worked. Everything engraved fine.
Thanks to all for the suggestions.