A little bit.  On the flanges, the bottoms hang over a bit into the spark plug area.  going to have to take some off all 8.   On the tubes, just a little bit of an indention on the #3 on the drivers side, and #7 on the passenger side.   I will probably use a 1" socket and just give it a good whack with a hammer to put a nice smooth round indention to give the wire extra clearance.   And it should be fine with heat sleeves on 3 and 7, but since I think it needs it on those two, I will most likely put them on all 8.  Cause they are like 28 for a set, or 6 dollars each.  

The headers were boxed Jegs brand, but they are Jegs packaged Flotech headers for an 1987 F 150 5.0 

Passenger header, is nearly identical to the Fox body factory header, just bigger tubes.  

Here is my original post, from the old forum, on the subject of modifying headers to clear things

on April 27, 2012, 9:30 amDaze wrote:

would you trade a few HP for ease in instillation and maintenance of a part??? I am putting a new engine in my Galaxie. When I put the headers in originally, and when I took them out the other day, they were a major pain in my rear because 3 bolt holes per header were covered by the tubes. In other words the only way to get the bots in the holes was to put them there before you installed the header and then you had to tighten them a bit at a time as the header sucked up against the block. Not to mention that once you had the headers in place it was hard to get a wrench on them so it was almost impossible to get them tight and just as hard to tighten them later. My solution was to bolt them up to an extra set of heads I had and gently persuade them with a hammer to clear the bolt area. So now I can not only easily get the bolts installed but I can also get a ratchet on all 16 bolts. I know the dents I added will slightly reduce my HP but IMHO ease of maintenance is far more important than a couple of HP. What do you think???

on April 27, 2012, 11:39 am Don R wrote:

Yes, us Ford guys have to do what you're talking about. It seems that the mfg's who produce aftermarket parts take exceptional pains and care to make sure Chevrolet parts fit and to hell with all others. As to headers, I've often wondered if they actually used a real car to mock up stuff. I had to look no further than my own car as I had my headers custom made with a block and trans in the car. I found some areas that could have had some improvements as related to bolts etc. It appeared that a small twitch here or turn a bend slightly one way or the other would make a difference in fitment and installability. So, I look at it this way, that our hobby is far better than being in a hospital or doing yard work. That's my rant for 4/27. Ha, 427, how sweet.

on April 27, 2012, 1:14 pm 70XL wrote:

Absolutely, especially in the situation you describe. It is way too easy to get obsessive over a theoretical HP number, that in reality will have no real impact on how the vehicle operates, or our driving experience.

on May 1, 2012, 2:43 pm jeff hann wrote:

I agree When I put the 5.0 in my 82 Mustang, I had the choice of using stock headers (newer model) or buying aftermarket. The stock headers are very pinched so the assembly line equipment can get a socket on every bolt. Aftermarket headers might give 10 HP. I used the stock stuff. 

on May 7, 2012, 10:04 pm Rog FE427 wrote:

I agree But your's is not as bad as mine 
A 70 Tornio with a FE427 with long cast iron headers. you have to lay the headers along the 
inside the frame and then drop the engine in and bolt them on with plenty of room. when installed 
they fit like they were made for the car instead 
of a Galaxie they even have a notch in them for the steering gear.

on May 8, 2012, 7:15 am BattlestarGalactic wrote:

I've had to "massage" headers for a few friends race cars over the years and NEVER saw a bit of difference performance wise. 

My favorite saying: "I think only WJ would be concerned with it". 

Warren Johnson, "The proffessor of Pro stock".