I have a nikishi custom sport. I busted the thread on the crank arm (the one with the sprocket) were the peddle screws in (dont ask, my dumb ass laizy mistake)

looking at the back of the peddle the only ovious marks i can find are 170, I am assuming its 170 MM crank arm set. Will any crank arm set work as its 170 MM,

Or can i use one from a 10 speed, I gone on ebay and i find some on there but they say they are for a 10 speed, i have a 12