Another option would be to
use a sender that will fit in the radiator petcock hole.
You would have to use a sender that comes on real low tho.
on @ 180
off @ 160
Could also remove the intake (not absolutely necessary) and drill and tap for another sender.
I'm sure there is a boss somewhere on the intake for an additional hole.
I just too a brand new manifold in to get drilled for a fan switch on my 66 Elky