Although it may not work with the SPF, I know that Tornado sells a good looking set of headers designed for their Coyote version of the GT40. Others are supposed to offer these as well I hear.
FWIW, I would opt for the Aluminator version of the Coyote and plan to do just that myself. It's made a good bit stronger, not much more money, and performs slightly better. With the new Cobra Jet intake for the 5.0, the horsepower will actually be better than the Boss version but may not be as conducive to daily driving.
Ford part# M-6007-A50NA
This is quoted from Ford on it:
"Ford Racing has taken the Mustang GT 5.0L 4V TiVCT engine and created another in its series of "Aluminator" crate engines built to deliver higher performance. The 5.0 Aluminator NA is built with extreme duty connecting rods and pistons designed specifically for high performance applications. Mahle 11.0:1 compression ratio forged pistons are hard anodized with Graphal low friction coating. The connecting rods are premium Manley H-beam with ARP 2000 bolts and fitted with BOSS 302 high performance bearings. "
The dyno tests were showing 10-15 HP over the regular Coyote if I recall correctly. With a Boss or Cobra Jet intake, this thing should make 450 or more RWHP if what I have been seeing about dyno pulls is correct.
Almost forgot...
The Aluminator is good to 8,000 RPM. The Cobra Jet is made to peak at 7750. Will make a heck of a potent combination and although won't sound like a high output 302 with a "bundle of snakes" will still sound plenty powerful.