Dude, let's be frank. The AC you have is a 13.5 made 15 years ago. It is not up to standards by any means. Buy two 15 K and install them. No, NOT 13.5.
You are up against serious heat and you will thank me for the advice.
On to another subject. Your 50 amp service will handle 12,000 watts of utilities. WAY more than the 3600 watts of a 30 amp service. No sweat on your system handling the load.
But do NOT have any faith in the existing AC unit.
Jim and DW 48 years Brenda
2019 F450, ruby red
Harley Road King & sidecar