I find thats a very common misconception. Either theres too many rumours around or they simply got a crappy example (but again age might be a factor too). So you may say age would be the reason why these car fails but if you've got one in really good condition, why would they break? Common reason why people rebuilt is maybe for security reason (not having to worry about old bits falling apart) or they're just after higher power.
sav_man's N1 is running 320 or 330rwkw with everything stock for Targa (except for catback, cat, ecu and ebc).
I for one have not spend any money on replace old bits that shits itself for any reason. Only time I paid for servicing/maintainence are oil change and CV boot replacement. If you're driving a Supra, I doubt there'll be much difference.
From what I read on builds RB26 and 2JZ are just about the best engine made for modding, so you cant go very wrong. Oh yea, you're after the 34s. That makes it even lesser chance of scoring a shit one.
Skyline: TS drives toyota... but its a TT Supra. Hahaha