SINGLE PLT IFR IN TWIN FREIGHTER OVERSHOT ASSIGNED ALT IN CLB.

Narrative

AFTER DROPPING OFF MY PAXS AT FORT DODGE; IA; MY COMPANY REDISPATCHED ME TO PICK UP SOME CARGO AT COLUMBUS; NE. THE FREIGHT NEEDED TO ARRIVE IN MINNEAPOLIS ASAP. AFTER CHKING WX AND FILING AN IFR FLT PLAN; I PREFLTED MY ACFT AND TAXIED OUT FOR DEP. THE WX WAS VFR WITH SCATTERED TO BROKEN CLOUDS AROUND 1500 AGL. I RECEIVED A CLRNC TO DEPART RWY 06 CLB AND MAINTAIN 3000. I WROTE DOWN THE RWY HDG (WHICH I DO NOT NORMALLY DO) SQUAWK AND DEP FREQ ADDING THE RWY HDG WHERE I NORMALLY WRITE MY ALT. AN SMA DEPARTED AHEAD OF ME AND TURNED L ALONG MY FLT PATH. UNFORTUNATELY; IT APPEARED HE WASN'T MAINTAINING LEGAL CLOUD SEPARATION. I WAS CONCERNED ABOUT THE VFR TFC. BEING DISTRACTED BY HIM; AS WELL AS COPYING MY CLRNC INCORRECTLY; I CLBED THROUGH MY ASSIGNED ALT OF 3000. ATC ADVISED ME OF MY MISTAKE AND I QUICKLY DSNDED TO THE APPROPRIATE ALT. I LEARNED TO BE CONSISTENT IN COPYING CLRNC (I NOW USE A FORM). DO NOT RUSH. NO TRIP IS AS IMPORTANT AS OPERATING MY ACFT LEGALLY AND SAFELY. HAD I WAITED WITH MY DEP; THE SMA WOULD NOT HAVE BEEN A TFC FACTOR (IRREGARDLESS OF HIS VISUAL SEPARATION). I WILL NOT ADD TO THE MISTAKE OF OTHERS.