"Optimal" gap doesn't really exist. The smaller the gap the slightly better the compression gets, along with squish depending on chamber shapes and compression heights etc. When on the minimum gap, the absolute concentricity of the bore matters: any taper, combined with thermal expansion will result in ring bind and piston failure. .016" will be absolutely fine and will err on the safe side in your case. Blow by does not occur until the gaps are much larger - well over .030". But if you start out there, there's no room for ring wear, which is most intense in break-in. Good luck and hope this helps.