In order to get the 351W to fit I had to cut the coil towers. I cut 
    horizontally above the upper A-arm in about an inch +/- deep. Then I cut 
    upward on each side and met at the top. When I was done cutting I had 
    an L-shaped hole (from the front).A professional welder friend welded 
    1/4 inch plate into the hole, a narrow piece horizontally and a larger 
    piece vertically. Mine looks very clean of course it takes a while to 
    figure out exactly how deep you can cut etc., leave enough room so that 
    the spring and the upper A-arm function properly. You also must be 
    careful of flex in the front end with the steel removed from the towers. 

    Even with all the refabrication I still had to dimple my headers 
    slightly for clearance (mine are Blackjack AlumiKote). 

    This is the only way I know to make it fit.  Let me know what you 
    end up doing. Good luck. 
    Click this link for a great article on this modification from Ford Muscle.com

    A note on Headers......
    BlackJack no longer exists. Any header that will fit a 302 in a Maverick
    may work in a Maverick that has my shock tower mods, with a little
    modification.

    The headers on my car have 1 5/8 tubes with a 3 inch collector. They are
    for a maverick with a 302 and are not a great fit but I did dent a
    couple of tubes to get by the steering box and they are OK. I too would
    like to find some decent headers. I've heard that early mustang headers
    for use with a 351W may be an easier fit with minor modification.
   Have you found a header that works well with a 351W? Let me know!!!
   E-mail me

    Autokrafters sells swap headers for a 351W in a maverick. They are 1
    1/2" tube and require Mustang motor mounts that will raise your engine
    by 2 inches and still require slight tower notching. 
    I don't recommend them. They are part number ES9. AutoKrafters
   A direct link to ES9 (click)