How can I run 640x480 NTSC 4:3 aspect ratio on composite to consumer CRT with RPi3 B+ running LibrecELEC 10.0.3 ?

How can I run 640x480 NTSC 4:3 aspect ratio on composite to consumer CRT with RPi3 B+ running LibrecELEC 10.0.3 ?

I doing the following below but is not true 4:3 640x480 NTSC.

"composite=1" to the kms dtoverlay in distroconfig.txt

dtoverlay=vc4-kms-v3d,cma-512,composite=1

Enable tvout in config.txt

enable_tvout=1

Set mode in cmdline.txt (on the same line after "quiet"). eg for NTSC:

video=Composite-1:720x480@60ie

The results is a squished image that makes eveything look tall and vertically long. It is not true 4:3 aspect ratio.

I've looked everywhere without sauccess. I would appreciate some help.