That is exactly what I did on my '67 Charger. I used two common bread pans for internal sump boxes (I have dual pumps) and installed trap doors on the all four sides. In practice, I should have fabricated boxes with much taller sides, as at a quarter tank it will starve for fuel pretty readily. However, the basic idea of modifying a stock tank has worked very well. I used JIC (37 degree flare = AN) bulkhead fittings with seals and wire passthrough fittings obtained from ATL for elctrical and fuel line plumbing.