Not wise due to too much metal removal in a 4 valve chamber. The metal removal will affect the plug heat dissipation too. The seat for plug gasket has to be recut as it is too small for bigger plug. Maybe the head has not enough relief to get a bigger socket in as well. Bigger plug tightens more so easier to crack too. The job with all 4 needs to be done on a machine to get all 4 holes straight, doing it by hand is a mistake.
Main thing is the plug is picked with the proper amount of metal around it to dissipate heat correctly, that metal not there will both weaken the head to crack easier and not make plug get rid of heat correctly too. You think there is no interference with the valves but they have to be kept away a certain amount from plug hole or cracking due to thinness of metal cross-sectioning then becomes an issue even if it looks OK. You need thicker there than just an eyeball says.