D-450 headers in early a flange question

So after 4 months my headers arrived for the 66’ Barracuda and a 273 engine.

Honestly I was disappointed as the welds look like poop. I am a welder by trade so those need to matter.

Anyhow I ordered the flanges welded smaller for the 273 head ports and they arrive with 340-360 ports. They are ceramic coated so I void the warranty if I weld them up myself. Summit does not know what happened and it’s another 4-5 month wait for replacement ones.

Long story short- the sealing surface is now very small. Any advice for making sure this seals outside welding flanges and the warranty is out the window? Almost $1000 for Mexican made quality. Very disappointed for sure.
Syleng1