Question about drawing spousal benefit based on deceased ex wife.

Asking for my BIL who was married to my sister for 17 years then divorced. She died at 53 (19 years ago) and never collected SS. He worked a job that under the WEP prevented him from drawing on her Social security when he retired.

Since they were divorced would he draw what would have been her full benefit or would it be reduced to half? Is there an online calculator where he can put in her social security number and find out the amount of her benefit? (LOL and by him I mean ME because he is "allergic" to computers, LOL.)