6.5.0u1 its just guessing... on 6.5.0 the old Client will work in some way for sure. Keep in mind that all new vSphere related features which comes out after 5.5 are not working in the old client.
I haven't say that you should install ESXi 7.x on your hold hardware. I have say that you need to install VCSA 7.x to get the new good working HTML5 vSphere Client to manage your old 6.5 Host.
And there is no need for "searching" something when you just can doewnload the 60 days Eval from vmware.com.
Regards,
Joerg
