Yeah, I have a CA downpipe from them too. The flanges and bends line up exactly with the OEM pipe I got from Jhot with my swap:
Their dump pipe matches the OEM one exactly as well.
As said, any SR dump pipe will work w/ the SR down pipe but apparently (secondhand information here) using the SR parts means the hanger on the transmission mount doesn't line up and the DP will hit the frame rail. I'd try to get a CA elbow from SSAC (
here) and get the down pipe you have chopped and rewelded to match.