looks like good old British Racing Green, Rolls saddle. Like you, my 653 is in fixed gear mode, Mavic MA40 rim, Shimano 600 hub, Concor Light saddle, Cinelli Giro d'Italia bars. The horizontal rear drop outs on these old frames make chain tension a lot easier to get right. I tried once to convert a more recent frame but vertical drop outs were a nightmare; I tried various combinations of front chain ring and rear sprocket, half links on the chain etc. but never really got it right.