Brake warning light - Proportion valve wire connection ?

I bought my 68 cuda after it had been converted to 74-76 manual disc up front. I believe they switched the prop valve from the donor car as well. The brake warning light has always came on when I apply the brakes. I have the cast style prop valve as seen in the picture. My warning light wire is connected to the front post on the prop valve. Is this correct or does it go on the center post.

Thanks