The Subaru crowd in the US is big on E85. The main guy on all the e85 forums, 'hotrod' has been running e85 in a near stock subaru of his for a couple of years now. The only things he has changed is the ECU and the injectors, only because the stock ones only just fell short of the 25-30% higher volume of e85 they had to put in.

Do a search for E85 on Google and you'll be sure to find that guy's name somewhere in each article.

Reading thru the subie forum, i think they said you use about 15% more e85, not all that much worse than normal petrol. I've seen a 1600 race car with a N/a SR20 with separate throttle bodies getting 209kw ATW with unleaded 98, and 214 off E85.

The best way to compare more/ less power is to look at the lower heating values of the fuels and then compare the stociometry.
Ethanol 28.865 MJ/kg
Octane 44.427 MJ/kg
I've chosen Octane but really the heating value is about the same for C6-C12 hydrocarbons.
Ethanol burns at 9:1 and petrol 14.6:1 so the equivalent heating value of ethanol in replacing petrol is....
28.86x14.6
----------
9
=46.8

So slightly higher than petrol supporting the argument of slightly more power with nothing but fueling mods for a high ethanol blend. You also get more cooling and potentially more air into the engine.

So engine changes are not needed (not required to change pistons or compression ratio).

Are these the only Fuel line/ tank mods required for e85?
* Tank must be lined
* fuel lines replaced
* Carb jets replaced with bigger ones

There are plenty of flex fuel vehicles so I'm sure a standard engine would be happy on e85 with a jet change and new rubber fuel hoses, assuming the pump is big enough and compatible.

The thing about lining tanks and metal fuel lines that I've read is soft metals like zinc, aluminium, lead corrode as the ethanol dissolves the oxide layer. The concern is a little extra water in the fuel. My feeling is in a dry climate where the car lives inside or the fuel is consumed and replaced regularly metal corrosion is probably less of an issue.

Since I don't drive mine much and am going efi I figure the right materials in the fuel lines/ tank will be cheaper than replacing 8 injectors. With a carb you could probably just see how it goes.

I had a look today and the tank sheet appears to be about 1.2-1.4mm thick. drained and drying in the sun.

The subaru's in question were flex fuel vehicles, but theyre only good for about 50/50 petrol and ethanol. any higher ethanol content and they have problems supplying up in higher revs (3000+), 'check engine' lights and what not.

But enough about them, back to the real cars.

After cleaning the tank it looks to be galvanised. Is it? or is it just really clean inside.

Probably just clean. To see if it's terne plate i think you have to heat it with a big soldering iron on the outside and watch for any melting on the surface nearby on the inside.