Something is not right with the front end of your PV. A friend of mine has a 59 that he raced back in the 60s and 70s. With only relatively minor modifications---competition brake linings, Konis, Goodyear Blue Streaks, roll bar (not an anti sway bar, but a hoop of 1 1/2" tube in the back seat area) and racing seat, it was good to go back then. It eventually got a B18, slighty tweaked (cam and reworked SUs) and 4.10 rear, at which point it would top out at about 105-110 MPH, with no instability problems, even when getting its doors blown off by Porsche 917s and Ferrari 512s at the Sebring 12 hour, circa 1970. This car also ran at Daytona. Again, no instability was noticed. As far as I know, apart from the Konis, nothing unusual was done to the front end.

This car is slowly being restored at the present time, to its original racing configuration. If you were at the Carlisle Import show last May, you probably saw it, as a freshly painted (olive green) rolling shell.