+1 Worksman has very strong frames and wheels; the forks are strong enough to bear a huge load, but they don't take "hits" too well..... Concerns, for me, would be braking (you can get the optional drum brake, but it's kinda weak, IME) and, of course, you'll need new pedals. Worksman oughta be ashamed of their stock pedals. I've heard the stock saddle doesn't fare well under lots of weight, but I always ditch those massive pieces of velo-furniture immediately. 7/8" seatpost is skinny; I've bent a few and I weigh 250, but to be fair, I'm usually bombing trails on these things. Last concern I'd have is with the track-ends/"drop-outs"; Worksman builds a bombproof frame out of heavy guage steel, and then uses paper-thin stamped drop-outs. Being the type of guy who deals with old/well-used Worksman INB frames frequently, I've seen a few with saggy drop-outs. So far, I've had good success with just torqueing down the axle nuts and whispering a prayer, but it does worry me.
Oh, and not at all related to rider-weight, but still something everyone needs to consider when deciding on a Worksman: They seem to paint their frames with children's water-color paint, and they seem to use seawater to dilute it, b/c your Worksman will rust, blister, and bubble in the first year. I buy ex-warehouse Worksmen all the time; they usually are heavily coated in surface rust, especially on the stays, and they tend to only be between 5 and 7 years old when I get them. The steel has always been solid once I ground all the rust down, and they tend to look good after a fresh coat of powder or a decent repaint. I guess the sub-par paintjobs are one way that Woksman stays affordable...