Jack, I just don't get it. You've got a perfectly good motor and you want to tone it down an bit. So as mentioned, it's easy and cheap!
1) Throttle linkages. Make them more progressive and limit the throttle opening! That will limit power and torque right away and is easy and free! My car was very difficult to drive with the original non-progressive throttle linkage. Much better now with progresive D type cable drum.
Even better, consider adapting an electronic instead of cable throttle. Then you can program whatever throttle curve you like into it. More throttle, opening more aggressively in the higher gears if you like. It's just simple electronics and you won't have to change a thing about your car and perfectly good motor!
2) Play with the tune in the ECU. Simple to retard the timing a bit here and there to knock out some torque. OEM ecu's do this all the time as part of knock mitigation and traction control strategies.
3) Smaller cam if you want. So put cam with 220 - 230 duration and a lot less lift, somewhere around 500 thou lift and maybe hydraulic roller since you don't rev it. That will tone it down (less lift will kill off your torque, despite the lesser duration). I've just put a cam very similar to yours in my 347. Solid roller, 668 thou lift and 257/265 duration at 50 thou. Similar induction setup to yours (DC&O throttle bodies). I wanted more power (racing). Went 443 RWHP at 6800 on Dynojet. Happy with that, but it does not have the monster torque that your 427 does of course.
But really - go with option 2 first (simple) then option 1 (little more complicated -unless you go a simple adjustable throttle stop - I have one under my accel pedal) before spending a lot of time and efffort to change something that ain't broke! Its' easy to go slower...wish it were easy to go faster!