I am running a surge tank under the bonnet. Dunno the legalities. but the factory pump feeds the surge tank and the efi pump feeds off that. I used another coupes metal line for a return line to the breather on the sender unit.

mines a coupe btw. think the tank setup is a little different.

Thats exactly what I had in mind bart but because the front edge of the sedan tank is the lowest side. The bowl going through the trunk floor would be in line with the diff so the diff would smack it on bump. I guess its not really an issue on 1600's with the IRS.
I completely went off the idea of ever having an external pump in the boot after going for a ride in dans ca 1600, that pump was mounted on top of the tap and it was absolutely deafening when sitting in the back seat. admitedly it was about 6 inches from my ear!
I guess I could make it internal so instead of dropping through the floor it sits up in the tank, with a few small holes around the bottom edge to let fuel in (but not out in a hurry)
............. so reading that again I mean just run an external high pressure pump under the car but have a "baffle box" around the outlet.

The BRE510 had like a surge tank welded into the bottom of the tank so that they could get every last drop of gas out of the tank. You could weld a short cylinder into the bottom of your tank, and have it drop through the trunk floor. This would serve a your surge tank. I'd also baffle it too, so that any gas in there couldn't slosh out under hard cornering. It would also eliminate the need for a lift pump. I don't know how noisy EFI pumps are, but my holley low press pump is rowdy as hell.

I had a hunt around looking at fuel setups for 1200 sedans and most people seem to be running surge tanks in the boot and external pumps. Which I really don't want to do (noise mostly)
Is there any other options other than getting the tank modified for an internal pump.
I had wanted to run a small surge bowl welded into the the bottom of the tank feeding an external pump. It would need to be located at the lowest point of the tank which is where the drain bung is, which is fine except that the drain bung is directly over the diff centerline meaning it would be a dual purpose surge tank/bump stop!
What are all you sedan guys running.
P.s I am running an sr20de
P.s.s. i want to keep my spare wheel well.