Sending unit

I am replacing the gas tank in my 1970 Duster 340. We want to replace the stock fuel gauge with an Autometer Sport Comp II electronic unit. Problem is the recommended Autometer sending unit won't fit this application so I need to find a compatible unit the fits in the stock location. According to Autometer this gauge will work with a unit rated for 10-73 ohms, or close. Goodmark makes a sending unit they rate at 10-70 ohms. Is this close enough ? It does have the single 5/16" Outlet I need. Also, I'm not sure if this is linear, or non linear. Has anyone else experienced this, and if so what was your solution ?