rebuilding from latest and kernel versions

[vm finance]

Hello,

I downloaded pre-built VM image of FreeBSD 12.0 STABLE from osboxes.org and
using that vmdk, I was able to get FreeBSD running under VMPlayer.
Kernel version (uname -a):
FreeBSD osboxes 12.0-RELEASE FreeBSD 12.0-RELEASE r341666 GENERIC amd64

I wanted to try latest TCP code so downloaded latest codebase on this VM:

*svn co svn://svn.freebsd.org/base/head /usr/src*

built a new kernel:
cd /usr/src;

make buildworld buildkernel

make installkernel

reboot

After reboot, kernel version is still the same, except its has osboxes.org:

FreeBSD 12.0-RELEASE FreeBSD 12.0-RELEASE r341666 GENERIC amd64.


Questions:

1. kernel version (r341666) hasn't changed after building latest...is
that expected?

2. Is it possible to label it differently and allow bootloader to pick
latest vs 12.0 published kernel?

Many thanks in advance for any pointers.