Foreman would always have a chance, he hits like a mule, is tough as **** and is one hell of an intimidating presence. Lewis would bumrush Wlad and destroy him within a few rounds, he'd take the fight to the inside and would push Wlad around, hold and punch and generally rough him up. Taking it to the streets as Steward once put it. Wlad wouldnt be able to hide behind the jab, he's a fantastic boxer but an average fighter, Lewis would brawl it out with him.
It took around 4 rounds before Lewis started going inside Vitali... And Wlad hits a lot harder than Vitali.
An active aggressive opponent with power, decent speed and good stamina. Someone that could cut off the ring and constantly throw. That kind of style could trouble Wladimir and force him to use his legs and throw punches.
Prime Lewis would have worn that version of Vitali down for a late stoppage barring a cut but thats an entirely different arguement. Vitali is far more game than Wlad and is generally a more awkward proposition to shut down, hence why it took so long for Lewis to get going and then proceed to butcher his eye. Wlad may hit harder but is easier to intimidate not for a lack of heart mind you when he does come under fire. When Lewis comes storming out for a scrap ala Golota or Grant fights Wlad's instinct will be to hold and cover up. It doesnt matter how hard you hit if your A. not throwing back or B. having your work smothered because you cannot keep your work at your optimum range, in Wlad's case long range.
If there was someone who was athletic enough to time Wlad's jab and deliver an overhand right, Wlad would be in a world of hurt. For that reason, Lennox Lewis would have been an absolute nightmare for Wlad.