As long as you have it temp and salinity matched, huge PWC's can't hurt IMO. I've done 90%-95% multiple times and only have experienced good results, my corals seem to love it, and lots of coral gets exposed to air periodically in the wild anyways.
Although with such high nitrates I'd suggest taking it modestly slow. When I've done massive water changes my parameters have already been near perfect. Drastic changes in parameters are never good.