This might be too late based on your later update, but I generally always play this formation and had pretty good success on FM21 with a fairly simple version, so here's a couple of things that might help:
You're playing a Target Man/Forward but have shorter passing and Play Out of Defence active, plus you want your keeper to distribute to your defenders. If you're looking to take advantage of his height, heading, jumping and his pace/OTB stats then I'd suggest you probably need to be going a bit more direct so the service he gets takes advantage of that in a more deliberate manner
For example: more direct passing, get your GK to distribute to him, and look at how you cross the ball. Should it be floated crosses so he can rise above the defence? Maybe hit early crosses to prioritise getting the ball into him?
Then, if he's winning in the air he needs bodies around him to capitalise as is mentioned earlier. CM(A) and an IF who can benefit from his knockdowns and flick-ons.
OR if you prefer the shorter passing style, perhaps he needs to be a DLF or PF so he's involved more and there's less contradiction in his role v the TIs?