Rockers: 1.5 vs 1.6

Ok for example. The cam I run now is a Lunati solid roller with .400 valve lift, intake and exhaust. I'm running 1.6 rockers so my lift is .640.640...I COULD have them grind me a cam with .427 valve lift , run 1.5 rockers and have the same .640/.640 cam. My question is which would be the best option?

Huh??? Is your valve lift .400 or .640?? How can regrinding .427 and using a smaller 1.5 ration equal .640??? From what ive seen going from 1.5 to 1.6 cant add that much lift on flat tappet, but it can on roller?

Jake