It sounds like you are trying to put a full basement in where a crawlspace was designed.
Generally, you cannot undermine a footing, at least not over its full length. There are probably guys that have seen it/done it, but it is not an acceptable practice. I wanted to do this to a property I was remodeling/adding onto in Saint Paul, MN, and the building inspector forbade it even before the permit was issued. Actually, I wanted to put a new footer immediately next to the old footer. He made me install the next nearest footer about 5' from the other one. That footer was 16" deeper.
The real story is what you are attempting to do isn't an acceptable building practice. In Minnesota, if you have a structural problem, or cause a structural problem, you can be held liable for failing to disclose it to new buyers. I don't know the statute of limitations on that law, but it seems fairly serious.
My best advice to you is to skip your plan of putting a full basement under the space. If I've misinterpreted your plans, please post a follow up message.
If you absolutely insist on making that space a full basement, you would probably have to have a building mover come out and design a support system that would allow you to remove part of the existing foundation, then another part, and so on, and frankly I wouldn't do it for any house. It would simply be too dangerous.
The only practical way that I can think of would be to build a new foundation wall, slightly bigger than the wall you have, with the footers at the appropriate depth, then build up the wall with the old wall still in place. You'd then sister all the floor framing, assuming the 14' dimension, you' end up sistering the floor at about say 16'. After that the structure would be supported across its length of 29', but it wouldn't be done on the sides, and the amount of material to remove is a lot.
I don't want to think about it anymore. Chimneys should also never have their footers removed, cracking is just about a 100% likelihood.