Notscrod here. I'm 5'-3" with 28" inseam male with a Wabi Lightning 42cm c-c with 650c wheels that has a 27.5" standover with a horizontal top tube and 23mm tires. I think the lowest standover you'll find in a track bike is 27" on the IRO Mark V HD, which has about a 1cm lower bottom bracket. The IRO seems to be perpetually out of stock, however. The Fuji Track with 650c wheels has a sloping top tube, but about the same standover due to a higher BB. This is what the Wabi Lightning looks like set up for me.