The logical next step for the local music collective that presented The Clash's "London Calling" live in its entirety was to move up to the band's three-record opus, "Sandinista."

		"Music of Elvis Costello" Where: Rex Theatre, South Side. When: 8 p.m. Saturday. Tickets: $12; benefits a foundation through West Penn Hospital to help local cancer patients purchase needed drugs.

But whoever said rock 'n' roll should follow logic, so the musicians have moved on instead to the Clash's most eloquent countryman, Elvis Costello.

Bassist Rod Schwartz, best known for his work in the local '80s band 11th Hour, leads the ensemble at the Rex Saturday night in "The Music of Elvis Costello."

The original idea was to do the brilliant first three albums -- "My Aim is True," "This Year's Model" and "Armed Forces" -- in order. Then, after meetings at Kelly's in East Liberty, they decided to do the first two straight through and then expand the concept to include the sweeping glance of his career, 60 songs in all.

"We did our best to try to touch on virtually every album in his career," Schwartz says. "We're not doing anything off the new classical record or the Bacharach [album]."

What the musicians had to deal with was complicated enough, even more so than with The Clash.

"You can't even compare the two as far as the challenge level. The Clash was more complicated than I ever thought, but the subtleties that are in the Elvis songs, at times it can be overwhelming. You'd be hard-pressed to find three better musicians than the ones he had playing for him -- Steve Nieve and Pete and Bruce Thomas. Each of them were geniuses at what they did. Every song they played was like the last one they were ever going to record."

The core of this band is the same as for the Clash show: Schwartz on bass; Kip Ruefle and Dave Klug on drums; Daryl Cross and Steve Seel on guitar; Tim Pollock on keyboards; and John Young, Mike Moran, Steve Morrison, Ed Masley and Harvey Coblin on vocals.

Schwartz says the arrangements are as faithful as they could make them, though, "thankfully, none of the singers are trying to re-create Elvis' voice. It would probably turn out sounding like a parody if people were trying to sound like Elvis. One guy on the planet sounds like Elvis -- and that's Elvis."