No, don't start twisting things without doing analysis first. Each component has a function, and trying to fix a truss rod problem by messing with the bridge because it's easier is foolish. First, if you don't know what you're doing, read carefully through the stickies in this forum to get some good background information. The truss rod's job is to set the relief in the neck and hold it there. While adjusting the truss rod will change the string height, that's not it's function. The bridge saddles are to adjust the intonation and the string height. They both work together with the nut to set up the bass. Plus you've got the body/neck angle to deal with ('though this one is generally set correctly at the factory and seldom needs to be changed).
So, start with the truss rod. Measure. How straight is the neck? You can't measure the neck without it being at tension, so tune it up to the pitch you're going to be playing it at with the strings you think you're going to use. If the rod is too straight and/or the saddles are too low and you just cant get the strings to vibrate open enough to get into tune, go ahead and relief the truss rod a little bit (about a quarter turn) and raise the saddles a little bit- you're going to pretty well have to start from scratch anyway with this project so just get it to where you can get the open strings in tune and don't worry about anything else.
Now, fret the lowest string at the first fret and the last fret (some people recommend using 17th fret) at the same time- that makes the string an acceptable straight-edge so you can see how much relief there is. Look under the string at the 7th fret and see how much clearance there is. I don't use measurements any more, but just eyeball it after 30+ years, but I go for a slight relief and my Lakland is sitting at 1/32". 1/16" is OK, but I wouldn't want more than that myself. That sets the truss rod. It'll probably move some for a few days because it's been sitting so long, so plan on readdressing this over the next week or so- the wood's going to move slowly. Make sure you don't pre-stress the when doing the truss rod adjustment so you don't trash the neck (and if you don't know what that means, re-read the stickies, and get a copy of Dan Erlewine's "Complete Guitar Repair"). While you're doing this, look at the neck to see if it's evenly bowed, of if there are high spots.
Now that the rod is set, re-tune and play it. If you still have problems ,then start adjusting the saddle height for how you want to play. There's no "correct" setting except what you like. For example, Fender's specs for both the truss rod and the bridge saddles are uncomfortably high for me, and I'm not a low action freak by any stretch. But play it. If you're still getting rattle at high frets, and you're pretty sure the neck is stable, just raise the saddles until it goes away. If getting rid of the rattle makes the strings too high for you, then you've got more problems- either uneven frets, a raising tongue at the high end of the fretboard, or the neck/body angle is off.
Again, read all about doing a proper set-up, and that stuff should answer specific issues. Just don't jump in and start twisting stuff without knowing specifically what that's going to do to the bass.
John
