Welcome to the forum. I own a MK II.I'm 6' 1" tall and weigh 240. I fit in it pretty well.From what I've seen the MKIV has narrower foot boxes than the MK II and are off to the to the sides a little more than the MK II. I think the foot boxes were made a tad smaller to fit the mod motors.You could open up the foot boxes and still fit in the LS motor.Roger