The How2Work body seems to be an adapted Medicom, and I don't expect Feng's head to work with it. I haven't stripped mine to see (don't want to stretch the sweater, which is a cotton knit), but the hands and wrists are Medicom, and the torso is a hard "fat shell." I expect it's similar in design to the ITPT Goerring of a few years back. I'm planning to use the Ignite body Feng suggested for his head, and let it be a superior companion piece to the How2Work.
There are other possibilities for his apparel besides the sweater, but the cheapest option to check is probably a sweater made for Ken. Try the Minibarbie store on eBay maybe.