I'm doing this right now on my S13, good news is theres a pretty comprehensive guide if you search SR20 S13 conversion by John Bennett I think his name is. The guide covers all of the required wiring harness modifications required to run the SR, depending on which model your SR came from. Good news also is that the SR fits straight onto the standard S13 engine mounts, as does the gearbox and prop shaft fit with no issues.
I'm yet to go at the hub swap, as far as I'm aware the rears are a straight swap as in the S14 hub fits to the S13 knuckle, brakes are a pretty straight forward fit... theres also a guide on that if you look in S13 Tech. The downside to your plan for me is finding an S13 shell which is in a better condition than your 14 for a decent price. Mine was sold to me stating it had little rust and actually had some pretty serious MOT failure-type rust hidden behind bodge jobs!
Hope this is of some help and good luck!