heads / valves

Putting a set of modified heads on my sbc 350. They are 14014416 heads taken out to 72cc. Studs and guideplates. Want to use manley street-flo valves. Removed the existing valves that fit snug and ran the manleys through. There was a bit of play. I measured the existing valves' stem and it came out to be .354" the manley's stems are .34". Can I run the manleys or is there too much play? I have a set of comp cams teflon valve seals that don't look to be able to fit the existing valve stems. Is .01 +/- .002 too much play in the guides or can I run these and be cool? Thanks.

If there's too much play in the stem/guide, you'll never be able to hold a good seal at the valve face/valve seat interface.