One of the most iconic beefcake moments of my childhood came in Mysterious Island, the 1961 adaption of the Jules Verne classic about some Civil War soldiers who end up lost on a mysterious island with giant crabs, prehistoric auks, and Captain Nemo. The 1960s version added some women to up the hetero-romance, but made up for it by divesting Michael Callan of his shirt. The scene where he and his girlfriend get trapped by giant bees is still frightening today.
Michael Callan was the go-to guy for teenage beefcake in the 1960s, wandering between Disney, ARP, and anyone else who would put a shirtless scene. I've seen him as a bulgeworthy circus aerialist in The Flying Fontaines (1959), a troubled high schooler in Because They're Young (1960), a teen dancer in Gidget Goes Hawaiian (1961), and a rascally cowboy in Cat Ballou (1965). He also took off his shirt in Bon Voyage (1962), The Interns (1962), The Victors (1963), and who knows what else?
Plots involve backstabbing coworkers, people suspecting their secret, and Greta's boyfriend suspecting that they're really involved, but no hetero-romance for Peter. You can see some episodes on youtube.
In real life Michael was married three times, and doesn't have a lot of gay rumors attached to him, though Dwayne Hickman spends many pages of his autobiography describing their warm friendship.