Valve Guides for Oversized Valves and Lead-Free Gas?

My 1968 225 is at an engine rebuilder in Phoenix.

I purchased a cam, springs, and oversized valves from Oregon Cam.

The rebuilder says I have a choice: either build the head for lead-fee gas or install the oversized valves. No valve guides exist (to his knowledge) that allow for both.

Is the rebuilder correct?

TIA

–Walt Jackson