Do you think 425 HP is a lot for a Big Block 1977 Ford F150?
Are you running a modified 400 or are you running a 460? Your question is abit to vague. How do you know you have 425hp? Has it been dyno tested? Is this 425 horses at the rear wheels or just the engine? Is it a short bed or long bed because that will make a difference launching off the line. Now is it an automatic or a stick? Is it a C-4 or C-6 or FMX or standard truck transmission? Because if your running over 400hp and putting it through a truck transmission it will never run like a car. And you can make a truck run as fast a car. Another question, was the Mustang a 302 or a V6? So you can see that you really do need to add more information to your question so people like myself that are into racing can answer your question properly. As far as trucks go, I have a 1975 Ford Club Cab 3/4 ton with a 460 that I punched 30 over with a torquer intake and a 780 Holley with Hooker Headers and Flow masters and I pull a back hoe with it. Because when I am unhooked I can smoke alot of cars. It depends on the car your running against and what you have got. I won't go into detail about the cam, ignition and other things. I have a C-6 behind it with a 2000 stall converter and a B&M shift kit. So every detail makes a difference.