Swapping tanks is easy, essentially once you jack up the car, Partially undo the 2 fuel tank strapscarefully lower tank slightly and undo the jubilee clips (most likely corroded), between fuel filler pipe and tankUndo the fuel lines going out of the tank from under the rear bench of the carUndo the vaccum hose into tankundo the fuel drain plug and use a funnel to drain fuel into Jerry cansUndo straps and remove tank. Swap in a new tank, Job done.
If you want the new lines to run outside of the car, I advise you clamp them onto the existing lines under the plastic guard. then run them through the small opening from passenger side into the back of the engine bay and route to the fuel rail. It can be done safely but is a fiddly job.
I've done this, as well as wilsonic for EG3's with Bswaps. You can find info on my build, as well as wilsonics. I ended up swapping to a standard (non-carb) tank, due a number of reasons, see my build: http://www.civiclife.net/board/topic/104801-zoaibs-b18-eg/?page=6 Off the top of my head though: 1) noise- i had my fuel pump mounted in engine bay- sounded like a bee hive even with rubber sleeves around the pump. 2) reliabilty- inline pumps are good for pushing fuel and not 'pulling', so my set up wasn't ideal. I would get air in the lines from time to time and it would cause issues 3) risk- looking back, I dont know why i didnt change tanks sooner. i had small fuel leaks all the time due to the joins in my plumping.. near a hot exhaust and engine- risk of fire. I initially thought I should mount it under the car and nearer to the tank, but I changed my mind when i found out how much easier a standard tank would be. BUT didnt change the fuel lines - thats a complete mission with lowering the subframe and what not. I run high pressure thick rubber (hard and not too flexible type) of hose, direct from fuel filter next to the tank, all the way to the fuel rail, and the same for the return. Theres minimal joins and reducers in the system, and its simple, easier, you can still run the lines on the underside of the car and attach them safely..