Hey,
I just finished my first fixed gear conversion too. I used an old 1971 Nishiki. If your bike is anything like mine, it had an old size large chain...the normal fixed gear size of 1/8". Multi-speed bikes use 3/32" i think. Due to this i was able to use one of the original front chain rings and original crank...just with new crank bolts for only one crank. It came with 44t and 54t rings... 44 works pretty well on hilly terrain with a 17 in the rear...I have a 16. I'm not sure what yours has, but the original rings on mine were Sugino.