Weird that Andy Warhol is credited with taking photographs, but not that cover photograph, which is credited to another guy. But that there seem to be no other photographs in the packaging according to that discog listing.

I can't be sure, but it's likely somebody else with the same moniker. Johnny Thunders' namesake had been lifted before the one we're talking about it got a hold of it, so it's possible a Euro session guy was using it, possibly inspired by the Kinks songs from '68, also of that name.

The link says the LP was recorded at Trident studios in London, might be an angle you could follow. Johnny Thunders, of Heartbreakers fame, would probably have had to belong to the musicians union to have been brought in for a session, which doesn't seem likely.

Then again, heroin is a helluva drug, and he could have cranked out hisself some disco for some scratch. People are known to do worse.

that said, yes ari the timeline you have is correct so when and where would he have worked on this?

as a treat, here is the other skyline track i have from this album, it's different, instrumental, but definately has thunders guitar work on it. it's sort of a call and answer between the drums and guitar.

Skyline - Future Jungle

this link also has the "warhol cover".

Don't know how reliable it is, but the date fits. That said, I agree with Dougsf that this doesn't say much about JT's personal taste, since money for dope (cue "Gimme Some Truth") may have been his primary incentive.