Thanks!

Frampton on the cover?

He's definitely not on these recordings.

I won't touch anything Cleopatra puts out.

'Rain" and "...Lovemaker" are on Street Rats, which was slapped together from various sources by A & M.
I don't know about the other tracks, but they are probably taken from other sources as well and may not necessarily be by the " classic" line-up.

As outlined from Ultimate Classic Rock site:

A Humble Pie album that's remained in the vaults since 1975 will finally be released next month.

Joint Effort comes out on Feb. 8, and finds the band recording in its own Clear Sounds studio between 1974 and 1975. But the album was ultimately rejected by their label at the time, A&M.

The LP's title reflects the work made by Steve Marriott and bassist Greg Ridley on a project outside of the band at the time. But after a stretch where Marriott unsuccessfully lobbied to be Mick Taylor's replacement in the Rolling Stones and the group saw its U.S. profile raised due to Eat It and Smokin', they reconvened with guitarist Dave Clempson and drummer Jerry Shirley.

http://ultimateclassicrock.com/humble-pie-joint-effort/