Upgrading from Mavericks to High Sierra - dual boot (Windows 10)

Currently running Mavericks with Windows 10 on separate SSD (legacy bios). Originally installed using chimera 2.2.1 My intention is to install a clean High Sierra OS on a new SSD. How do I successfully incorporate the Windows 10 SSD after installation. My motherboard supports UEFI but my assumption is that since the Windows 10 SSD was installed using legacy bios that the High Sierra OS would necessitate using legacy bios as well. (Hopefully my ignorance is not showing here as I'm very much a novice) Should I consider a new Windows 10 installation utilizing UEFI after the clean High Sierra install instead of using the existing Windows 10 SSD with legacy bios?

You only need to select Legacy mode install for Clover after you install HS. Suggest disconnect Win10 drive while installing HS and only reconnect after you have HS booting from SSD.