All the s13 cams are the same as Im aware like posted. If your super super sceptical I could run a part # search off of my best friends (nissan technician) girlfriend (service writer)...
The s14 cams are exactly junk either... They could be usefull in conjuntion with the s13 cams a FI motor to shift the curves around slighty
As far as I have ever heard there where only 2 different DOHC cams... an intake and an exhaust and in the case of the nissan motorsports cam, a transexual (repinned exhaust hehe) intake cam.
Whoever told you a ton of valvetrain work is envolved should be kicked in the groin btw... I put 150k mile (the car happened to be a 91 but if it was a 93 I would have pulled them anyway as the FSM lists the same duration and spec in the 93 as in the 91) s13 cams into my 75k mile s14 motor. I checked the shim clearances and you know what... it was in spec on lobes. If it wasnt its not like its very difficult to do a little math pop one out and put a new one in.. Not exactly modifying the VT in my book.