Amp settings - Les Paul on a Marshall amp

I've tried various tone settings by starting with everything set a 5 and then tweeky up the high and mid and lowering the bass but I just can't dial it in. So I just want to know if you could help me how do I set up the tone for a Marshall JCM 2000 using a Marshall 1960A cab plugged in by a Gibson Les Paul 1960 guitar to get a sound that is not muddy and has that airy Jazz tone found in Steely Dan. Please advice me any initial settings to begin with(??) I need it for my guitar lessons...
Thanks.