Snoop Dogg is about to make Le'Veon Bell's rap dream come true -- telling TMZ Sports he's absolutely down to blaze a track with the Steelers running back ... but there's a catch. 

FYI, Bell isn't just a beast on the field -- he's also pretty good on wax ... with his mix tape racking up more than 100k plays on SoundCloud. 

In fact, the last time we got Bell out, he told us he was trying to make a collab with Snoop happen -- since he's not just a rap legend, but a hardcore Steelers mega-fan. 

Well, good news ... we just got Snoop and he says he's into the idea -- as long as Le'Veon gets his legs healthy!  

You're welcome.