How much spell power do casters need to match Classic damage?

In the Forever beta, caster spells had their base damage cut sharply while their spell power coefficients were raised, so they catch up as you stack spell power. Below is the extra spell power Forever needs to reach Classic's base damage (at 0 spell power), at level 60 with the highest rank and DoTs over their full duration.

Priestavg +73

Shadow Word: Pain+75
Mind Blast+75
Mind Flay+72
Devouring Plague+70

Mageavg +109

Fireball+211
Scorch+179
Pyroblast+172
Blast Wave+78
Cone of Cold+78
Arcane Explosion+77
Fire Blast+75
Frostbolt+74
Arcane Missiles+73
Frost Nova+69

Warlockavg +224

Immolate+419
Soul Fire+366
Corruption+320
Bane of Agony+308
Shadow Bolt+282
Searing Pain+255
Drain Life+200
Hellfire+91
Siphon Life+80
Death Coil+75
Drain Soul+70

Druidavg +257

Moonfire+322
Wrath+290
Starfire+159

Shamanavg +534

Chain Lightning+715
Earth Shock+596
Frost Shock+568
Flame Shock+440
Lightning Bolt+353

Key points

Priests and Mages mostly need +70-80, which early gear covers quickly. Mage fire spells are the exception (Fireball 211, Scorch 179, Pyroblast 172).
Warlocks take big hits on their core spells (Immolate 419, Soul Fire 366, Corruption 320), while Drain Soul and Siphon Life barely change.
Druids and Shamans are hit hardest. Chain Lightning needs +715, so the gap is biggest while leveling and in early gear.