The Barbados Demon,a sawed off powerhouse, who fought on even terms with some heavweights. How would he do in this era of 147pounders?
I think it would be hard for him to overcome his height and reach disadvantages. Plus I'm positive today's Welters are a lot quicker than those Heavies of yesteryear that Walcott fought.
He'd make 130, possibly 126. Against modern 147 pounders he might struggle due to lack of height and weight but his punching power was undoubtedly real and has to be considered.