It is better to be too loose than too tight. Usually the valves hammer the seats and tighten up on the clearance. I don't think being that much over will hurt. It is only .030mm. I'm in the same situation as you. Measured my valves and have two on the rt cylinder at .330 and .335. I want to get them around .227. I'm getting some backlash tools made for the cams. Triumph dealer is 8 hours away so hopefully the local Yamaha dealer keeps enough shims in stock so that I won't have to wait for them with the bike apart.
