ACFT VECTORED FOR APCH HAS TCASII RA FOR LGT ON TKOF OPPOSITE DIRECTION.

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INBOUND TO SPOKANE WE WERE VECTORED FOR R TFC TO RWY 21. WE WERE CLRED FOR A VISUAL APCH JUST PAST THE APCH END OF RWY 21. WE SET UP ON A 3 MI BASE WITH THE FO FLYING. THE FO CALLED FOR GEAR AND FLAPS AND THE LNDG CHK WAS COMPLETED. ON BASE WE WERE INFORMED OF AN OPPOSITE DIRECTION 727 FREIGHTER ROLLING ON THE RWY. I REMARKED ON THE TWR FREQ THAT THE SPACING LOOKED CLOSE. TWR ANSWERED THE SPACING WOULD BE ALRIGHT SINCE THE 727 WAS ASSIGNED A R TURN TO THE E AFTER TKOF. AS WE ROLLED OUT ON FINAL I ASKED THE FO TO DISPLACE THE ACFT TO THE W AND ANGLE THE APCH INTO THE THRESHOLD TO INCREASE THE SEPARATION. AT APPROX 2 MI ON FINAL THE TCASII WARNED WITH A TA AND I SAW THE 727 BEGIN A R BANK TO THE E. A FEW SECONDS LATER THE TCASII WARNED WITH A 'MONITOR VERT SPD' RA. I HAD JUST ENOUGH TIME TO NOTICE THE VERT SPD NEEDLE CONFORMING WITH THE GREEN ARC GENERATED BY THE TCASII WHEN IT CHANGED THE COMMAND TO A 'CLB -- CLB NOW' RA. MY ASSESSMENT OF THE SIT VISUALLY CONFIRMED THAT THE ORIGINAL TCASII COMMAND WAS THE BETTER COURSE OF ACTION. THE 727 WAS PROBABLY TOO LOW TO GET A DSND COMMAND EVEN IF HE WAS TCASII EQUIPPED. CLBING WOULD HAVE TAKEN AWAY THE VERT SEPARATION WE ALREADY HAD ESTABLISHED (WE WERE LEVEL WITH THE 727 CLBING AND WE DSNDING) AND A TURNING GAR MANEUVER IS NOT SOMETHING WE TRAIN FOR AND PROBABLY WOULD HAVE RESULTED IN A LOSS OF VISUAL CONTACT WITH THE ONCOMING ACFT. I TOLD THE FO TO HOLD THE APCH PATH AND TO IGNORE THE CLB RA. I ASKED THE 727 OVER THE RADIO IF HE COULD INCREASE HIS TURN RATE. AT THIS POINT IT APPEARED THAT EVEN THOUGH THE SEPARATION WOULD BE CLOSE THE BEST COURSE WAS TO LET OUR DISPLACED APCH PATH AND HIS CLBING TURN TAKE CARE OF THE SIT. THE 727 TURNED MUCH SLOWER THAN I ANTICIPATED AND THIS RESULTED IN A 400 FT LATERAL SEPARATION WITH 100 FT VERT. IN RETROSPECT I SHOULD HAVE NEVER ACCEPTED THE SIT BECAUSE MY FIRST IMPRESSION WAS THAT THE SPACING WOULD NOT WORK. ONCE ON FINAL WHEN IT REALLY BEGAN TO APPEAR THAT THE SEPARATION WOULD BE CLOSER THAN I AM COMFORTABLE WITH; I BELIEVE WE WERE CORRECT IN NOT TURNING ABRUPTLY THAT CLOSE TO THE GND. IT SHOULD BE EMPHASIZED THAT AT NO TIME DID IT APPEAR THAT WE WOULD HIT THE OTHER ACFT. THE FO REACTED VERY WELL TO MY DECISIONS ON FINAL AND THE COM WENT VERY SMOOTHLY. I WILL NEVER ALLOW ATC TO PUT ME IN A SIMILAR POS. NONE OF MY OPTIONS ON FINAL WERE VERY GOOD ONCE THE SIT HAD DEGRADED AND SEPARATION WAS LOST.