Walcott would be better served trying a run up top for a few games. He's stocky enough to have a stab at holding the ball up and he's got the pace to go the other way too and work the channels or get in on goal, which will keep the defenders on their toes.
The Richarlison experiment hasn't worked for me. He's all over the place up there, doesn't know whether to move across the line or come deep and he very rarely goes the other way, which means Gomes is constantly working the ball from left to right and back again as there's nothing ahead of him. Gomes has the final ball in his locker, he just doesn't have anyone with much pace or genuine movement to execute it to. Keane always looks up for a runner too and has the ability to turn defence into attack if it was on.
Someone in the mould of Vardy would be perfect. It could be Walcott, or as near to it as we've got in the squad until we get someone in.