David & Clark conversion?

My brother is a helicopter pilot in the military. He gave me a D&C
H10-76XL headset. I understand that there is an impedance issue with
using a military headset in GA. So, I began looking for an impedance
adapter. In doing so, I found what I thought I needed. But, after
doing a little more checking, I'm finding that the H10-76 and H10-76XL,
specifically, are said not to work with the impedance adapter. In stead,
some sites recommend simply getting a heli-GA plug and replace the
dynamic mic with an electret mic. I've done some googling and find
conflicting reports, so it's hard to know for sure exactly what I need.
In some old posts, some people say that the adapter will work while others
say they won't; following up with supporting statements that the mic does
have to be replaced.

Any so, now my questions. Does this mean that my headset is actually a
high impedance headset? If not, why don't I need an impedance adapter?
Why would I need to replace the mic? Can I simply get away with using the
dynamic mic? If not, what's involved with replacing a mic on this
headset? Soldering required, or can I simply unplug the old mic and plug
in the new one? If I send it into D&C, what would it cost to have them do
the conversion? Estimates?

Thanks in advance!

Best Regards & Happy New Year,

Greg