Is the Seaguide HSC SCMSHSC reelseat mount over the rear grip? And does anyone know if it will work with NFC's soft touch rear casting grip?

According to NFC it will, right inmthe discription of what reel seats will fit, near the bottom of their info. Simple question that will help you from now on in rod building, would it be more prudent to build something that fits existing components, or would you want to go one off and probably lose market share due to special requirements and new component needs?

Yea, I was told the same with Batson CF casting grips (same as CFX) and Fuji split casting seat. OD to OD has maybe 3/16ths of an inch difference. The Seaguide reel seat appears to fit over something, but I cannot tell if it is over their own carbon tube or what.

Look at the measurement of the inside of the reel seat it is the same as the OD of the back of a 16 mm casting seat, the same as the tube grip OD, the same as a casting cork grip OD, the same as a CFX casting grip for a standard casting reel seat made by everyone. Just learn to spend the few minutes we all had to spend pre-internet and when something doesn't auto-fit, make it fit, it's what rod building is all about.