TMZ Sports spoke with the former MMA fighter ... who tells us he's tired of BKFC guys seemingly ducking him -- and his sights are now set on boxing the 50-0 legend.

"I've called out several names in the BKFC and crickets," Palomino said. "I called out Chad Mendes in three consecutive fights when they signed him, and I heard nothing."

"I'm looking for the big money fight," Luis continued. "My biggest one that I have in mind, and I think it makes perfect sense, will be Mayweather."

Luis tells us it would be a great business move if the two men -- considered the greatest in their respective sports -- collided, adding he's willing to fight Floyd in "his world."

"I'll put the gloves on," Luis said. "And I will represent Bare Knuckle, boxing with the gloves on, but I'm representing the dark side. I like to call it the dark side."

Luis respects Mayweather's legacy -- but says it's time for the former champ to fight someone who can legitimately hold their own against him inside the ring.

"The last [fight] that he did, he's having fun in there, but there's no type of competition," Luis said. "I know that being the champion he is, he still needs that."