(morning - possible new whm owner here.. 1st post)
As an operator of a small hosting company for many years running nothing but FreeBSD
It says in the docs that amd64 7.0 is supported..
if you did a 7.0 install then a buildworld up to 7.2, I would think everything would work as long as you did not do a make delete-old-libs (and such)
obviously any new apps that would be built would be linked using the newer libs.. but the old ones would be lying around for (somewhat) compatibility..
(right?)
Or does cpanel not work this way?