Hi bill, all,
A good place to start would be b&c aircraft electrical supply out of newton KS. Bill bainbridge and family run, a regular at oshkosh as a vendor. Buy a book called 'the aero electric' by bob nuckells. Will give you the basics about EAB aircraft wiring. Peruse thru the website. You will want to buy tools, ie ratchet crimper, d-sub crimper, strippers, coax tools, etc. they have d sub pins. U can use the solder type , or crimp type. Individual pins, male and female.
Im sure noel can give you solid advice for mgl specific info.
Be sure to use shielded wire for anything to do with the radio , intercom , headset jacks etc.
Yes we learned also that the efis throws out alot of noise, we worked a year on eliminating noise into the radio system. We have a dynon 7 in skyview.
Good luck on wiring your plane.
Lots to learn also fwf. The book is good at explaning how to wire it up. Components, wire sizes, etc.
Www.bandc.aeroWaiexN143NM
Michael