What is the correct ownership for subdirectories in /usr/local After a few reckless uses of chomod (and some history I don't recall, apparently) I currently have the following ownership in my /usr/local:

drwxr-xr-x   13 Rax   admin   Caskroom/
drwxr-xr-x   87 Rax   admin   Cellar/
drwxr-xr-x    3 Rax   admin   Frameworks/
drwxr-xr-x   17 Rax   admin   Homebrew/
drwxr-xr-x    2 Rax   admin   Library/
drwxr-xr-x    6 root  wheel   MacGPG2/
drwxr-xr-x  654 Rax   admin   bin/
drwxrwxr-x   16 Rax   admin   etc/
drwxr-xr-x  118 Rax   admin   include/
drwxr-xr-x    4 Rax   admin   info/
drwxr-xr-x  438 Rax   admin   lib/
drwxr-xr-x    3 Rax   admin   libexec/
drwxr-xr-x    5 Rax   admin   man/
drwxr-xr-x    7 Rax   admin   mysql-utilities-1.5.3/
drwxr-xr-x  111 Rax   admin   opt/
drwxr-xr-x    3 root  wheel   remotedesktop/
drwxr-xr-x   42 Rax   admin   share/
drwxr-xr-x   10 Rax   admin   texlive/
drwxr-xr-x    6 Rax   admin   var/


Is this the correct default ownership for current (≥ 10.12.5) macOS? Should I change some of these (back) to root:wheel?
Out of the box - root:wheel has ownership of /usr/local and 0755 permissions. It's really up to you what you want. Since you clearly have homebrew or remnants of that, I'd do whatever brew doctor says you need to do for the user account you want to run things. I'd say keeping user:admin permissions is just fine for almost all cases in that part of the directory.

I have user:admin and 0775 permissions on everything but /usr/local itself and /usr/local/remotedesktop which match and are root:wheel with 0755.