FLC OF LTT OVERSHOT ASSIGNED ALT DUE TO ENG INDICATION PROB.

Narrative

AS PNF; I MADE THE STANDARD (COMPANY) ALT CALLOUTS OF '1000 FT TO GO' AND '500 FT TO GO' DURING OUR CLB TO 12000 FT. SHORTLY AFTER PASSING 11700 FT MY FO (PF) POINTED OUT THAT THE R ENG'S FUEL FLOW EXCEEDED THAT OF THE L ENG BY ALMOST 20 PERCENT. I LOOKED TO SEE WHAT THE PROBLEM MIGHT BE -- IF ANY -- AND COMPARE THE FUEL FLOWS WITH ENG TORQUE AND OTHER PARAMETERS. MY FO APPARENTLY 'JOINED' ME IN LOOKING AT THE ENG INSTS -- AT THE EXPENSE OF HIS ALT AWARENESS. I WAS (LIKEWISE) FIXATED AND NOT PAYING MUCH ATTN TO HIS/OUR PERFORMANCE. LOOKING AT THE FUEL FLOW AGAIN (AFTER COMPARING OTHER ENG PERFORMANCE PARAMETERS; I NOTICED THAT OUR VSI'S DISPLAYED A CLB -- RIGHT THROUGH 12300 FT. I POINTED OUT TO HIM THAT WE WERE STILL CLBING -- HAD WE BEEN GIVEN A HIGHER ALT BY CTR (THE CLRNC OF WHICH I'D MISSED). HE RESPONDED 'NEGATIVE' AND PUSHED THE NOSE OVER. WE REACHED 12500 FT AT THE HIGHEST ALT. WE WERE DSNDING THROUGH 12300 FT WHEN CTR QUERIED OUR PRESENT/ASSIGNED ALT. NO COLLISION HAZARD CONFLICT OCCURRED. I SIMPLY FAILED TO PROPERLY DIVIDE MY ATTN WITH THE DISTR OF A SINGLE ENG PARAMETER BEING OUT OF NORMAL LIMITS. MY FO; AS PF; ALLOWED HIMSELF TO BE DISTRACTED LIKEWISE. WE WERE LUCKY; AS THIS AREA IS NORMALLY VERY BUSY WITH OTHER INST/VFR TFC.