A KING AIR C90'S PRIMARY INVERTER FAILED AFTER TKOF CAUSING EHSI AND EADI FAILURES. THE PILOT RECOVERED FROM UNUSUAL ATTITUDES AFTER ANOTHER INVERTER ACTIVATED.

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I DEPARTED ZZZ ARPT IN FOG JUST BEFORE XA00 AM. I WAS THE SOLE OCCUPANT AND SINGLE PLT OF A C90GT; ON MY WAY TO PICK UP PAX IN ZZZ1 FOR A PART 91 FLT. I WAS ON AN IFR FLT PLAN AND HAD COMPLETED MY PREFLT CHKS AND DEPARTED AS INSTRUCTED ON RWY HDG 240 DEGS UP TO 2000 FT MSL. I ENGAGED THE AUTOPLT; AND TWR TOLD ME TO FLY HDG 270 DEGS AND SWITCHED ME TO DEP. I WAS ON THE 270 DEG HDG LEVELING AT 2000 FT WHEN DEP INSTRUCTED A R TURN TO HDG 330 DEGS AND CLB TO 3000 FT MSL. I INPUT THE HDG CHANGE AS I WAS LISTENING; AND THE ACFT STARTED TO TURN. I MAY HAVE INPUT THE NEW ALT; BUT AT THAT MOMENT MY EADI AND EHSI BOTH WENT BLANK WITH FAILURE ANNUNCIATIONS ON THE SCREENS; AND I RECEIVED 2 WARNING NOTICES ON THE ANNUNCIATOR PANEL WITH THE MASTER WARNING FLASHER. I EXTINGUISHED THE FLASHER AND ACKNOWLEDGED THE INVERTER FAILURE AND AUTOPLT FAILURE ANNUNCIATIONS. TO THE BEST OF MY RECOLLECTION; EVENTS UNFOLDED AS FOLLOWS: I TOLD ATC I HAD A PRIMARY FLT DISPLAY FAILURE AND THAT I WAS UNABLE TO COMPLY WITH PREVIOUS INSTRUCTIONS WHILE I DEALT WITH THE PROB; ASKING HIM TO STAND BY. I EITHER DECLARED AN EMER AT THIS TIME OR IN A SECOND RADIO XMISSION. I CHKED TO SEE IF CIRCUIT BREAKERS WERE POPPED AND IF MY RMI WAS PROVIDING HDG INFO. I SWITCHED TO THE #2 INVERTER AND EXTINGUISHED THE RELATED MASTER WARNING FLASHER. BOTH DISPLAYS ILLUMINATED AND WHILE MY EHSI HAD RETURNED; I BELIEVED MY EADI WAS INDICATING ERRONEOUSLY. I DIDN'T TRUST MY PRIMARY EADI; SO I FELT IT WAS UNSAFE TO ACTIVATE THE AUTOPLT. I XCHKED THE EADI WITH THE R-SEAT ATTITUDE INDICATOR; FOUND THAT THEY DIDN'T AGREE; AND CONCLUDED THAT THE R TURN HAD INCREASED AND THAT THE ACFT WAS IN A DSCNT. I FELT DISORIENTED AND KNEW THAT SAFETY OF FLT WAS AN IMMEDIATE CONCERN. I FOCUSED ON THE R-SEAT INSTS AS I TOLD ATC I WAS STRUGGLING TO CTL THE ACFT. AIRSPD APCHED THE BARBER POLE LIMITATION SO I REDUCED PWR; ROLLED WINGS L USING THE R-SEAT ATTITUDE INDICATOR TO LEVEL MY WINGS AND APPLIED BACK PRESSURE TO THE YOKE TO STOP THE DSCNT INDICATED ON MY PRIMARY ALTIMETER. THE LOWEST ALT I OBSERVED WAS 800 FT MSL.