If I understand your question correctly, you're asking what would be the highest DALPA could ask for without being unreasonable? (Unreasonable being the threshold for "lack of respect".)

My personal opinion is the high water mark in terms of compensation for Delta pilots were the last pay rates from Contract 2000, which IIRC took place in 2004.

In terms of opening pay rates anything significantly above those rates (after adjusting for inflation) would be unreasonable, but I would also include the work rules and benefits from that contract (and make an adjustment for the change in retirement plans).