I agree to listen to those bands yet their was some effects being used on those basses (not a lot but some). At the very least Compression but I can gaurantee you that all of those guys had some tricks up their sleeves( The OD circuit that Jack Bruce had built into his Bass, etc.). Besides the options were a bit more limited back then.
Oh of course there are exceptions, but personally I don't count compression as an 'effect', more a utility device, as I would also count eq.
And yes, lot's of these guys employed overdrive/distortion to some extent, some more than others. Jack was famous for his farting tone (which apparently John Entwhistle hated - he got around the issue in question by playing closer to the neck and getting a rounder tone). For many, it was just a result of driving tube amps hard. Hell, listen to Lemmy from Motorhead, an example of very overdriven bass that sits in the mix perfectly.
Others like John Deacon in Queen would have multiple signals, mic'd amp and DI. Tim Commerford from RATM/Audioslave splits his signal to multiple amps with different levels of gain.
Still, I believe it's what they played that fills out the sonic space more than effects. If effects are on the OPs bill though to get the maximum from their setup, I would suggest compression to get as loud and as smooth a signal you can (whilst retaining some punch and dynamics), overdrive (perhaps a Tube Screamer derivative) to get that tube amp growl - which has the bonus of enhancing harmonics, and lastly if you fancy trying one, a sonic maximiser. Some people poo-poo these devices, but IME, used subtly they can make a merge amp sound quite a bit bigger - just be careful not to overdo it, or else you'll lose the mids and definition, which thus defeats the object of the exercise!