My "new" 68 has a 451 stroker based off a 400 block It has power steering and headers with Schumacher mounts. It's a handful to drive compared to my 340 68.
In what way is it a handful? Far too many of these big block conversions had nothing done to the suspension. I've put 600 miles on my son's 440/4sp Dart convertible in a weekend. It's basically got stock big block suspension (torsion bars and sway bar). It's not a handful at all. My other son's '67 fastback (383/4sp) has 1.14" torsion bars and 1.25" front sway bar along with a rear sway bar and home built heavy duty spring stack. It was EASY to drive and not harsh at all.