I recently took a big fellow through the personal preferences of fitting a TW to himself. This particular bike will be used for putting about the man's woods and fields, with the occasional fair weather ride to town.
1) Handlebars. At least 2 inches taller, and being broad-shouldered, 2 inches wider. This is about as high and wide as the stock cables/hoses will fit. This will provide a comfortable hand position for the stock seat, but is still a little low for offroad. The angles of the stock bend are very good, but for big people, to low and too narrow. We ended up matching up or buying longer cables and hoses for a total of 4 inches additional lift, with slightly less sweep than stock to maintain a comfortable wrist angle, which goes to crap when bars are rotated excessively. 4 inches is too high for highway use with the stock seat.
2) Seat. Hand carved (electric carving knife) very hard upholstery foam three inches higher than stock, in the middle, tapering on the bottom to match the stock seat pan. The new foam is actually 2 inches wider than stock, too. Once affixed to the seat pan, the stock cover pattern was modified to fit, and a local upholstery shop stiched up a new cover. At 6 feet tall, I find the seat edges biting, but at 6-5, the owner has no problem.
Note that the densest foam available was used for this seat. Soft foam has too much give for a long ride. The thickness of the foam increases the preceived softness, and a heavy person can easily use up the travel in a soft foam, rendering the additional unladen seat height useless as far as opening up the angle of the knees--critical to comfort.
3) Shifter. Longer. Matched up to one with a folding tip. No idea what it is supposed to fit.
4) Footpegs. Larger footpegs were tried, but the stock pegs were preferred by this rider. He always wears work boots with steel toes and shanks.