That 27 years is a lot of time; I would be wary and do a test (bottom paragraph). There is the possibility of mottling of the emulsion from long-term cold storage; this has been seen in 120 and also 35mm film.
Post-testing (next paragraph), add 1.0 to 1.5 stops for every decade that has passed since expiry. It is E6 film and will lose speed over time. Very old Provia can shift to purple, rather like what one normally sees with this film in long-exposure star trails (a heavy purple cast). Incidentally, there are 14 rolls of RDPIII in my freezer, all expired in 2015 so they will need to be re-indexed at eventual loading/exposure. But in your case, almost 30 years... that does require a planned approach!
If you want peace of mind, grab one roll of the film and expose at box speed. Process normally (no push, no pull). If that single roll is one of all in a batch, good to go from there with the same rating.
Critically examine the positives on a lightbox for anomalies and go from there. Watch for anomalies in shadows (but not totally black) and highlights (but not spectrals) and mid-tones. A colour cast, as mentioned above, may be evident.
I would strongly recommend you expose the film in diffuse/hazy/overcast light so the film is not influenced by unduly very strong or point light; E6 film presents excellent results in diffuse light — leave bright light stuff to negative film.
