Why not just look at any data sheet?
Almost all of the data sheets, the good old ones from Motorola, TI, Philips, ect, all specify exactly what happens with their 74HCxxx's and 74HCTxxx's input and output thresholds, current drive and propagation delays with Vcc at 5.0v, 3.3v, 2.5v at a bare minimum.