I'm thinking the reverse operation would be a polarity issue but don't want you to smoke something on my say so.
I would call Smiths directly as you are getting signal response albeit 180 out.
So technically you're almost there...
This may be of help.
https://thefactoryfiveforum.com/show...hometer-hookup
https://www.svtperformance.com/forum...oyote.1035562/
On page 70 (this is Ron Francis wiring)
https://www.factoryfive.com/wp-conte...in-Hot-Rod.pdf
http://www.ronfrancis.com/images/CY15-INST.pdf