Peter,
Don' t waste your time with the tee off of the sending unit idea. I have mine hooked up that way and it doesn't work. The
oil temps are always real low because there in no
oil flow over the sender.
I looked all over my block {351} trying to find a "good" port but with no luck. The only way to get an accurate
oil temp is a fitting in the oil pan or if you have an oil cooler or remote filter in one of those lines.
David