Here you have the most recent Harbour version built using BCC64 bits:
https://github.com/FiveTechSoft/harbour_and_xharbour_builds/blob/master/harbour_win64_bcc_2020_05_07.zip
The most impressive fact is that it gets automatically built from GitHub Actions
https://github.com/FiveTechSoft/Harbour_builder/blob/master/.github/workflows/harbour_bcc_64.yml
Everytime that you may want the most recent Harbour version built using BCC 64 bits all you have to do is go to that URL and click on the "Star" button at the top
and GitHub will build it and will provide it to you just done