Even back in the 70's I knew I was being spoiled listening to Danny Gallivan. He was always in a class by himself. He was better than Foster Hewitt, a man with the type of irritating voice that, ironically, could never get hired to broadcast anything today if he were around. He coined a lot of the phrases used by all hockey announcers, but aside from the lexicon, his claim to fame is that he was the first. Other than that, he wasn't much fun to listen to. My only true exposure to him was when he did the 72 Summit Series and I found the way he pronounced Yvan Cournoyer's name to be really annoying (Cor-NWHY-yay) His son Bill, who did the Leafs games in the 70's, was equally bad. With him, Rejean Houle's name was one word "Rayjenoole". Both father and son had that nasal, whiny vocal style that, I guess, was popular on radio in the 1930's but which I found hard to listen to.
Aside from them, there was Ted Darling, ex of HNIC, who did the Sabres games on Channel 2 out of Buffalo. He rambled like an auctioneer while doing play-by-play. Then there was Dan Kelly, who had a booming voice. He was right up there with Gallivan but he didn't have Danny's vocabulary (no one did) Jim Robson is a secular god here in BC but back in the 70's you would have had to live on the west coast to hear him much. But he was pretty good and he got to do the 1980 Cup finals between the Isles and Flyers. He called Nystrom's Cup-winning goal in overtime. Back then, Bob Cole mostly did radio (CBC used to air games on radio into the 70's) and got the occasional gig on TV, mostly during the playoffs or when one of the regular guys was off. Kelly's "day job" was calling Blues games on KMOX in St. Louis plus other TV work in the States so he wasn't always available for HNIC.
It's fair to say that lightweights like Gord Miller, Jay Randorf and Jim Hughson would have been hard-pressed to find work in broadcasting back then.