It's your money but i wouldn't touch it, the carnk is probably a 5140 crank. You really can't buy good Chinese parts for that price, and know that they meet specs. Again i'm not knocking the builder, but he's going to build the motor on your money, after you pay him and maybe it will be delivered in 2 wks. but maybe in 6 weeks. Again it's your money and i think you have had some good advice here.
Just my .02
zip.