Book time estimates
The chains are noted in my computer at work as a non wearing/ rarely wearing item ( never seen that in reference to timing components). I can say that mine at 88K is BRAND new looking and did not need replacement. Book estimate time is 10.5 hours which is alittle outlandish but as I think about it, not unrealistic. I'd leave it alone personally, I doubt it has worn, I've heard stories of 200k.
BTW, dont let the chain slip, it'll be a pain to get back into time and it is an Interference engine ( piston impacts valve) if it is out of time.
86 300E 88k miles
99 Crew Cab Chevy Dualie 7.4L