Killer Shrike has converted older editions and his website has TONs of good information.
http://www.killershrike.com/
You'll find direct conversions of D&D to HERO somewhat tricky to do because some of the D&D spells are overpowered as !@#$ for their level and the points based nature of HERO makes those spells have to be downgraded substantially.
The classic cheese spells of D&D 5th edition (banish, hypnotic pattern, force wall, force cage) can be recreated roughly in HERO, but they won't be as crazily overpowered as their counter-parts.
I've done a lot of on-the-fly conversions using some rough rule of thumbs such as:
Armor class:
Converts directly to Resistant PD / Resistant ED in HERO. Chainmail adds 6 to AC (16) so in HERO it is 6pts of rPD/rED. Plate Armor adds 8 to AC (18) so it is 8pts of rPD/rED.
Add the DEX bonus part of AC to DCV.
Add the shield bonus part of AC to DCV.
Example: You have an NPC with a D&D AC of 20 (10pts above starting value of 10) wearing chainmail and a shield. Chainmail = 6pts rPD/rED and the NPC gets +2 DCV for the shield and +2 DCV for DEX.
Spell Levels:
Level 1 = 30 active points (max).
This goes up by 7.5 pts per level in a medium-magic setting.
You could raise it by 10 or more per level in a high magic setting.
Ex: Magic Missile (1 pt NND RKA, Autofire, Single Hex, Accurate, Does Body)
Level 2 = 37 active points.
Ex: Hold Person - Mental Paralysis 1d6 (+1 DEF).
Level 3 = 45 active points.
Ex: The classic Fireball - 2d6 RKA with an 8 meter AoE
Level 4 = 52 active points.
Level 5 = 60 active points.
Ex: Cone of Cold - 2d6 RKA - Area of Effect Cone - Armor Piercing
Level 6 = 67 active points.
Level 7 = 75 active points.
Level 8 = 82 active points.
Level 9 = 90 active points.
Ex: Meteor Swarm - 2.5d6 RKA - 8 meter AoE - Autofire
Saving Throws:
One approach - Add a -1 limitation to all spells that they are either completely negated or their damage is reduced by half if the target ties or wins a characteristic roll vs. casters spell casting ability.
Zapperon has a Magic Skill of 15 or less and he blasts Ser Rogerio with Cone of Cold. Ser Rogerio must make a Constitution roll (13 or less for him) and make the roll by the same amount or more than Zapperon to take 1/2 damage.
Other Options:
To retain a more Saving Throw feel of D&D compare the spellcasters OCV to the targets Characteristic / 3.
Ex: Zapperon has an OCV of 7 and Ser Rogerio has a Constitution of 18 (18/3 = 6) so Zapperon will need to roll a 12 or less (11 + 7 OCV - 6 DCV) to do full damage to Ser Rogerio.
Reverse rolls for a more "Saving Throw" feel.
Ex: Zapperon has an OCV of 7 and Ser Rogerio has a Constitution of 18 (18/3 = 6) so Ser Rogerio will need to make a CON save of 10 or less (11 + 6 for CON - 7 for OCV) to resist 1/2 the damage of the spell.
Weapon Damage: Use the weapon charts. It doesn't conver well.
Attack Bonus: Remove the STR bonus from an NPCs attack bonus and add that to OCV.
Hope that helps a bit.
