Wait Reem will slip some banned substances into hisown food so that he fails the post fight drug test.
Reem has a glass jaw but good defense and Bigfoot isn't really a KO puncher, he doesn't have great technique striking and that equates to lumbering punches with no snap on them.
I don't think he can get Reem down.
Basically, to answer the OP.. He can't.
I am not convinced he can't take him down but it will be with great difficulty and I think he will get KO'd first. He is a really bad match up for BigFoot.