After sleeping on it I think there's a better way forward!
I've been thinking about this for many years and collecting bits - I did have an abortive attempt at welding a sump on the bottom of a spare tank I had, it would've sat in the wheel well. I managed to fabricate the sump which was leak free, but I couldn't weld the tank to the bottom without holes being blown in the underside of the tank - a good idea let down by my lack of skill !!
If the feed from the top was going to be enlarged it would require welding plus I'd then have to get the feed pipe and associated plumbing sorted.
So seeing as I need to get something welded to the tank I might as well get a boss welded to the bottom corner of the tank.
I've got a fullbore stop cock with AN-8 tails on it
I'm going to get a professional to weld an AN-8 fitting on the bottom corner. As you can see from the picture there's enough room for the stop cock.
The top of the tape is around a quater of the way up, so as long as that's as low as I allow the fuel to go the outlet will be covered
As there'll now be a head of fuel feeding the pump I think AN-8 will be big enough but will defer to experts advice seeing as nothing has been done yet and this is a once only job so I might as well do as right as it can be done!
Views etc appreciated.
Cheers,
Pete