I'm about 230, and have no trouble with any of my Sturmey axles. Spokes, depends on age and condition. I had some on my 71 Continental pop just while truing them. I'd recommend building the wheels with some nice stainless spokes for insurance. The only parts of that bike I would worry about are the spokes, seat post clamping issues, and tire inflation. The seat posts have to be done tightly on those bikes, given the clamp thickness, small diameter, etc. The frame may bend if really stressed, but I've never seen a broken electro forged Schwinn. Has anyone else?
If he wants a more modern cushy saddle Wald makes posts with bigger tops to fit most modern seats . You can also change the clamp out, but I've found that an iffy solution. Most of them are narrower than
modern rails, not to mention the splines might be worn out.,,,,BD