Deleted member 33385
Is this frame any help? https://www.aliexpress.com/item/2030657141.html?spm=2114.12010612.8148356.9.3d496c5bIR3KJn
You could buy a motor kit from Mr Woosh. It gives the measurements down the page. Might need a long seat post. I have bought from them - they are trustworthy.
Cor! Only weighs 3.8kg! Very nice...