Ok, so you have standard 42mm chainline. Any standard singlespeed crank will work for you, though you probably won't be able to reuse that bottom bracket. Lots of people like the cheap stuff from FMF or bulletproof, or there is flashier stuff out there. However, 32t is smaller than what will fit on even the smallest road cranks, so if you want to keep running this gear you will need MTB stuff or a new rear gear.