what search argument did you use?
Dim memories from my electronics schools in the late 70's. What I did not know is that LED's look reactive because in this case, they are operating in an AC environment. XL=2×pi×f×L. Inductive reactance increases proportionally to frequency. Add to this, we do not have accurate numbers for voltage drops on "white" (blue and yellow mixed) LED's in whatever configuration the MFGR has decided to sell us.
That is why at face value, it is better to work with DC (or rectified AC) with LED's in general, and in high RPM (frequency) specifically. Thus that $8 Voltage Regulator on the end of a full wave rectifier would result in a solid system without worrying about resistor legs turning cherry red beneath electrical tape shoved in a head lamp assembly. (grin) I know I am preaching to the choir, but I see people all the time, spending serious money on engine guts, then turn around and get the cheapest crap possible to make the rest of the machine work. As it is, he is already turning the maximum voltage for either of his lamp selections.
I'm sure the set up you are sending him will work out just fine. You will never match sine waves with your dual coil mag set up. (Called paralleling in the generator world, if it happens, things explode)