Their recommendation is odd for why they recommend the other spring, and I know it says it in clear print, been their forever, but the duration of a cam has very little to do with the required spring pressures, I ignore it
You could run either of those springs, closed pressure is the same. However, the MAX springs have more open pressure at just about 310-315 with your cam.
The ones I recommended will be closer to 280
Either set will work, their recommendation will be slightly more dangerous at break in, but could hold in a little higher RPM once broken in, but if you are running stock rockers you really don't need the extra pressure, they are pretty light.
If you are confident you can light it right away for break in, their recommendation is fine but if you go with the big ones, be sure you are comfortable with break in
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 445 cid FE, headers, RPM intake, 1000 HP series Holley, 4 speed