428 street,
As anticipated, and learned first hand this weekend, I joined the crowd of people who learned first hand what the weak link is when applying too much FE HP/torque to a Jag IRS.
If you are buying an ERA with 428 and Jag/IRS, you may not want to go too wild on cam/power, etc. No need to go crazy. There are no tires but slicks for traction, and it just makes for more broken parts. Under 500hp (450hp) would be my preference on this car with this setup; unless you want to put a 9" straight axle in your car.
Good Luck.