Only 300 DOHC from Cobra R's rated at 380ish hp, that is why that one was irrelevant, they only made 300 Cobra R's, Navigators are everywhere, they have DOHC 5.4's, they are rated at 300 HP, Cobra's were rated at 305...Cobra swap is easier...
Former owner of 94 Bird with DOHC 4.6L swapped from a mark VIII
2011 CTS-V Wagon
1968 Torino was an original 289, C4, fully documented numbers matching car. Now: DOHC 4.6L/T-56 swapped, Cobra intake, IMRC delete, BBK long tubes and H pipe. Dynotech Aluminum Driveshaft, 9" rear with TrueTrac and 4.11's.