To Seal or Not to Seal
 

Hello all,
I'm working on the fuel tank for a 69 911E. The tank sat half full of gas for about 20 years and was pretty rusty on the bottom. I used the gravel technique to get out all the nasty stuff and it looks ok other than being red and rusty. I'm trying to decide on the next step.
I've read alot on these boards and the common answers are either seal the tank or just leave it as is and maybe put another fuel filter between the tank and the fuel pump. A repro tank would be another option but money is a bit tight.
Results with POR-15 seem mixed. Sometimes works good; sometimes just flakes or peels off after a while and creates another problem. Is there another product out there with better results?
I haven't read too much about leaving it in a chunk free but rusty state and just adding another fuel filter before the pump. The porsche manual says the tank should be drained once a year anyhow. Is this a viable answer? If so, what kind of fuel filter should I use?
I'd appreciate any input, guidance or tales of woe and success.
Thanks.