Yes Julian - it is LP only - and its on the scarcest of their albums called simply "100 Proof" Hot Wax HA 712 from 1972.
The track also gained release, early 90's, on a 45 on the Sophisto-Soul label - listed as being by Chuck Barrino - but the record is identical.
When the Acetate was found and played, nobody knew at the time, for sure, who it was and word had it that the artist was one of the Barrino Brothers - hence it was played as 'Chuck Barrino' and pressed on the 45 as such.
Soon after, we realised it was LP only and featured the magnificent vocal of the one and only Steve Mancha!
An absolutely awesome record. Your lady has great taste!
Good luck.
Sean