I think that there'd actually be much more opportunity to reuse stock footage. Footage from the movie could certainly be recycled. I assume that the costumes and sets would be, especially if they re-used the actors.
Remember that this was an era before Beta, VHS, Youtube, Cable or the 500 channel universe. Movies were only shown in theatres, and after the first run, would tend to have fairly modest circulation. Television reruns were only beginning. So potentially, you could use stock footage from Lost World or contemporary or prior movies and get away with it. Hell, the 1930's Flash Gordon used stock footage stolen from Stroheim movies or wildlife documentaries.
And yes, it probably wouldn't be very good by our standards. But Forbidden World was an 'adult' sci fi movie at its time, and its entirely possible that a television series version of Forbidden World would still have gone for that adult demographic, as opposed to children's shows like Tom Corbett, Rocky Jones or Space Patrol.
Another problem with Tom Corbett and Rocky Jones, was low budgets, live performance and often the fact that these shows aired as serials, sometimes several times a week, so there was an immense amount of padding.
At the very least, I think we could expect stories roughly comparable to the sci fi movies and westerns of that time.