CORP PLT USES WRONG UNICOM FREQ; HAS NMAC IN TFC PATTERN.

Narrative

AFTER CANCELLING IFR FLT PLAN WITH ORLANDO APPROX 5 MI FROM DEST; I WAS ADVISED OF NUMEROUS TARGETS IN THE PATTERN AT KISSIMMEE. I PROCEEDED TO THE ARPT FOR LNDG. I TURNED TO FINAL APCH FROM ABOUT A 45 DEG L BASE; ANNOUNCED MY INTENTIONS ON THE CTAF FREQ. AT ABOUT A 2 MI FINAL ANOTHER SINGLE ENG ACFT TURNED FROM A CLOSE L DOWNWIND ONTO FINAL IN FRONT OF US. I DETERMINED THAT I WOULD NOT BE ABLE TO SLOW ENOUGH TO LAND BEHIND THE ACFT. I SIDESTEPPED TO THE R; RETRACTED MY LNDG GEAR AND DUE TO TFC ON L DOWNWIND; I INITIATED A R DOWNWIND FOR ANOTHER ATTEMPT TO LAND. AT THAT POINT THE PAX IN THE COPLT'S SEAT ANNOUNCED THERE WAS TFC PASSING OVER US. I WAS UNABLE TO IDENT THE TYPE OF ACFT; BUT IT APPEARED TO BE SOME SORT OF A RESTORED WAR BIRD. THE WAR BIRD APPEARED TO BE APPROX 500 FT ABOVE US. I CONTINUED MY TURN TO ESTABLISH A R DOWNWIND AND LANDED WITHOUT FURTHER DIFFICULTY. AFTER LNDG I FOUND OUT THAT THE CTAF AT KISSIMMEE HAD RECENTLY CHANGED; AND ALTHOUGH MY CHART WAS STILL CURRENT IT DID NOT REFLECT THE CHANGE. I FEEL 2 THINGS COULD HAVE PREVENTED THE CONFLICT. #1 -- COULD HAVE CONTINUED MY UPWIND LEG UNTIL PAST THE DEP END OF THE RWY; AND THE TFC IN THE PATTERN; THEN TURNED TO A L DOWNWIND TO BETTER BLEND IN WITH THE TFC. #2 -- I COULD HAVE SWITCHED BACK TO THE ORLANDO ATC FREQ AND GOT THE MOST CURRENT CTAF FOR KISSIMMEE.