Hi, yes all three tanks that I modified have had fuel in them. Fuel in liquid form will not burn, it is the fuel vapors that ignite easily. Two of the tanks were done without any welding. On the latest one though, we drained the fuel out, then blew compressed air through the tank around all the crevices to make sure there was no liquid left in there ANYWHERE. When I didn't see any more fuel and only a slight smell remained I then turned on the shopvac and blew air through it for another 5 minutes or so. Then welded the flange on.

8" might be a bit on the shallow side for these senders. These have about 1 to 1.5" inches of compression built in to them so they always stay pressed against the bottom of a tank. My best suggestion is to just go to your local Pull-a-Part, and drop a few tanks and check out what is there.

The pressure shouldn't be any problem at all, it works just fine for TBI.
Fittings and plugs will be different, but not hard to sort out.
The level senders I used in the write up came with both ohm ranges for different applications, then later they changed style to the one pictured in post 22. These, I believe, were only available in the newer ohm range.

I hope this works for you.