Looking at StL, they'd have over 1500 IP per season through 1979 without drafting any new pitchers or waiving old ones, 1393 IP in 1980, 1438 in 1981, 1322 in 1982, 1610 in 1983, 1845 in1984… looks like they are a franchise owners might try to acquire pitching from with some trade offers.
Pittsburgh: 1451 IP in 1977, 1256 in 1978 (cccp, did you include Don Robinson?), 1240 in 1979, 1212 in 1980, 1079 in 1981… The random extra pitcher adds around 100 IP each season. They would definitely need to shore some pitching at some point, whether by trade or by draft, but they have time to deal with it.
Red Sox: 1417 IP in 1977, 1873 in 1978, 1855 in 1979, 1588 in 1980… don't worry about the red Sox, and don't forget they have great trade bait anyway: Fisk, Lynn, Rice, Yaz, Dwight Evans, George Scott...
Montreal: 1253 IP in 1977, 819 in 1978, 884 in 1979… They'll definitely need help. Nockahoma might regret drafting them. Gary Carter should probably be traded for some IP, maybe Andre Dawson too. I'd imagine they could get a lot of IP plus a competent catcher and outfielder in return.
These numbers are from loading the 1977 rosters, then advancing one year at a time and adding rookies. They might be a little off, more likely underestimating how many IP are available if I missed someone coming off injured reserve.