A return fuel filter? I'm not going to take this any further than this one more question because I don't want to derail and I don't want to seem like I'm arguing..
The only mod or extreme I've heard of for an Edelbrock carburetor is to drill the opposite side or the driver side of where the fuel comes in tap and make a bypass line that comes out... Take a line coming from that through a pressure regulator and run it back to your tank... Ad a high-volume fuel pump and you have a constant Rush of cold fuel circulating through your carburetor that's back pressure regulated and the rest of it circulating back into the tank....
Still he didn't have a heat soak problem before and now he does? I think we're both thinking it's something electrical that's following him, but nothing should be ruled out..