Spurs have Kane, too, and Chelsea started Giroud up front this past week. Lukaku is big enough, even if he isn't a true target guy.
We aren't really playing a 4-2-3-1 in the way Silva wants to play it unfortunately. I think he is playing more of a 4-3-3 in the way that you described with Gana in the back. RIcharlison and Walcott we thought would be the inside type forwards, with Digne and Coleman providing attacks and service from the outside. Coleman isn't capable of it unfortunately. Gomes also just isn't quick enough to truly play it that way as we keep giving the ball away and he can't stop the counter. It's really all Gana, but at least Gomes takes care of the ball.
But it's obvious we can't take care of the ball enough to break down a side that is packed in. Poor decisions and passing skills combined with poor athleticism is a complete disaster.