How to select and electric propulsion system for my experimental Ultralight? I've been trying to design and build, my experimental Ultralight using electric propulsion system, My plane designed base on Slaler and Gensis ultralight , following is the primary calculation

Empty weight 120KG

Wingspan 9.1

Length 2.8

cruise speed 120 Km/h

propulsion 20kw

I'm trying to select a pair of Brush-Less Direct Current motors (BLDC) for my airplane, but I have no experience using BLDC's before, whereas there is a lot of BLDC ambiguous options (mostly in Aliexpress) which claim to be a different KW.

My design goal is to find the best possible options for propulsion to have longest possible flight time duration.

Following is the 3D image of my design (located in my GrabCAD account)
any advice really appreciated
FLÜGEL World Directory Of Light Aviation 2019/2020 - English PDF could be a good starting point. On pages 278 - 281, a total of 71 lines of electric motors from 42 manufacturers are featured. Disclaimer 1: some data fields are incomplete for many of the entries. There are German, English French and Chinese versions in paper and pdf, starting at €8. Here's the paper version in German:
Welt-Index Ultraleicht und Flugzeug 2019/20 Wings of the World

In any version, the aircraft listings themselves may also be of interest, as aircraft models which are available with electric motors as the primary powerplant are highlighted with a green e icon. In browsing those, you may glean some emperical inspiration in terms of electric motor vs aircraft size. Disclaimer 2: the power-plant details for the aircraft listings are not always complete.

The free annual e-flight Journal by the same publisher includes motor manufacturer adverts which may be of some use.

Lastly, at the end of the online Kitplanes 2020 Engine Buyer’s Guide are four electric motors from one manufacturer.

Final Disclaimer: I have no vested interest in these magazines, publisher or any products listed or advertised.