The only time a YJ tub would hurt the value is if it was being sold as a "complete restoration" but still had all the YJ differences like the roll bar spreaders, swing out tailgate etc. Things that a purist looking for a completely oem jeep could use as bargaining tools
CJ's are in no way an investment so if it's rust free, built how you want and at a price you are ok with just go with it and don't worry about "value".
'84 CJ-7: Yota axles (spartan locked front, e-locked rear) 4" BDS, 1" Daystar & 3/8" shackle lifts, 35" X-Terrains on steelies, YJ Tub & family roll bar, heater blower upgrade, 4.2L w/MC2100 & Team Rush, Warn 8274. Rebuilt 4.2/4.0 hybrid, AX15 and twin sticks/clocking ring waiting to go in.
The advertised position for a topless, dirty jeep girl has been filled......by my wife. Thanks to all that applied.
<------------and yes, that is her. :-D