I have one, modified top end and cam. In the process of upgrading to proper headers and side pipes to uncork it. Bob Bennett of Bennett Coachworks in Milwaukee is almost ready to start producing a complete bolt on header/exhaust for the Excalibur. Web site is
Milwaukee WI Hot Rod Builders | Auto Restoration Services | Vehicle Updating | Bennett Coachworks. Knows these cars from preproduction days.
Never had high speed steering instability. Lots of wind buffeting and some front end lift. If there is slop in the steering shaft joints or lack of proper toe in, high speed steering could be an adventure.
Send me an email at mduke8 AT gmail.com and I'll forward you a registry of the cars with specific info about many of them and an info sheet about the specs, history, repairs and parts for these cars.
Interested in learning about your car.
Mike