I suspect that crank, which seems to be an older Ofmega model, does use the thinner tapered end spindle. You'll have to find an Ofmega BB to match up to the crank the, otherwise, other brand ISO tapered spindles might not fit far in enough into the square tapered holes on the crankset. Not sure if the Ofmega/Avocet connection means that some Avocet spindles might work. Avocet spindles are easier to find than Ofmegas at eBay.

Chombi