Looked up the sprockets over at WEMoto -
Click Me - the 91-93 model is listed as 14/43, later ones are 15/43. The later rear sprockets have a different spacing across the centre, judging by the drawings they have, fronts are the same. If it feels stressed then I'd be looking at one or two more teeth on the front - you'll get more relaxed cruising and the loss of 'off the line' acceleration will be hardly noticeable.
As for a thumper commuter, pretty much any middleweight thumper can hack it - the choice is down to you and your preferred style - sit up 'n' beg on a trailie, down'n'dirty on an XBR/SRX or something in between like an Enfield/SR/GN. Me? For a daily commuter I would pick the sack o' tatties riding position on an Enfield/SR etc. - although Wee Arfur the XBR is pretty nifty and comfy enough on a run, and Miss Whiplash my old 650 Dominator could hold masterclasses in traffic filtering ..... decisions, decisions!
You're welcome