Here is what I've heard about 1LE tanks-they are supposed to be like 18 gallons and have a swinging pickup in addition to the baffles.
Here is what I know about my 5 cars,none have a bigger tank and none have a swinging pickup.Now again I could be wrong and 1badTTA maybe your right and they were using TTA tanks in GTA's in 89(mine is an 89).
With regards to the original question though,I belive any tank will pretty much work,after all the modifications are on the inside so visually it will be perfect.And I don't belive they sell a specific 1LE tank anymore,if I'm not mistaken there is only one service replacement.
Again,I could be wrong
Steve