geddy lee? john entwistle? sounds like sansamp territory, my friend.
but +1 on the fulltone Bass Drive, but make sure its the mosfet one, i had the original and wanted that raging SVT tone, but couldnt find it. the clips of the Mosfet version ive heard are fantastic.
also if neither the sansamp nor the bassdrive are your thing, then how about the EHX English Muff'n tube overdrive? i used to run a eq pedal with a gain and mid boost into it to get a fantastic entwistle tone out of it, i've had two, but sold them both as i dont really trust the lowend on most guitar pedals, but there are many happy shoppers here that will tell you the Muff'n is amazing and has great lowend.
dont know how cheap these pedals are for you guys, but new in Britain all three range between the £120-160 mark, having said that i paid £112 for a used BassDriver DI, £85 for the original Fulltone Bassdrive, and my last Muff'n cost me £55, all used, all from ebay.