I think Liston would take this, probably by KO he's not Foreman who is only dangerous for the first 5 rounds he can be in there till the 15th if need be. Walcott certainly has some moments , probably makes Liston look silly at times but i think he might walk into something major at some time. All of the greatest fighters Walcott faced he always managed to get tagged badly and either dropped or KO'd and i think Liston punches harder than any of them.