This is not a cost effective idea. Sell this place and buy a single story please.

I think you'll need to get possession of the house first. There's too many variables, such as what was done to the rest of the house at the time, and what are the mechanical systems. After all, you don't know if there any bedrooms on the first floor now. Yes, it can be done, but I don't think anyone can even throw a wild guess at it without more info. 

One thing to consider: you'd have a hard time convincing a bank to loan you money to do it, as you would be decreasing the value of the house.

How old is the house?

The house is about 10-15 years old for the first story. 2nd story maybe 5 years.

We have a house in the family

Which seems to imply that you won't have 100% say so,

You don't like 2 story houses but you're OK with high ceilings and a loft.

The house has a lot of sentimental value but you're OK with changing it.

It has been at least 5 years since you have even seen the house. How do you know that you won't like it?

A fire or, in Cali, an earthquake could get it before you do.

The sentimental value comes more from the lot (amazing 1 acre) than the house since the one built 10-15 years ago replaced the actual house I grew up in. While it’s in the family, having grown up there for my formative years it’s understood that the place means more to me than others. As stated above, I don’t like 2-story homes so I’m just trying to get a sense of what it would take to make the place something I would actually like again. My hope was to get some information on what this process would entail so I could make my own judgement if the sentimental value and my architectural preferences outweighed the undertaking required.

My mistake. Should have known the internet would respond with snarky, unhelpful quips instead of actually answering the questions I asked in an effort to learn.

OP: you're not in Kansas anymore. You're in houzzland, the land where the munchkins will eat you alive. On the other hand, you haven't provided much information. If you want to know how much, it's $100k-500k to do what you want.

daisyandalex, Will you own the land next year? Wait until then, take photos and lets start from there. Depending on where it is, sometimes the land is worth more than the house.

Sorry, I understand. My Dad, after my mother died in 1998 after 50 years, married the b***h from h**l, for only a year and a half, who took everything.

You may can redo the house, you may can save the land, or something.

Essentially until you and two or three contractors walk the house, you don’t know what is involved. Most of us are trying to tell you cost is local. Forty miles from my house to the next city is a different world of cost. The most important comment, one that carries the most weight as far as I am concerned, is Seabornman’s. Only an in-depth, in person assessment of everything that has to be done to make it perfect for you. Do stairs have to move? Is there a massive stone fireplace in the middle of the space you want to have a new kitchen? Is the former living room now a giant master bath? We don’t know until you take possession what you want done so we can’t even guess what it would cost. We’re not mean, but most of us have built and or remodeled several times and we are realistic. Please don’t be angry-you are asking an open ended question. Can it be done? Yes. Should it be done? It will depend on the actual cost at the time you can bid the project and if you decide it will be worth the money to you. Oh dear! I just reread and noticed “ the amazing lot”. The cretins who bought one of our former houses destroyed the beautiful patio, plowed down the strawberries and the asparagus bed, cut down the flowering tree outside the breakfast room-for starters. The husband of one of my neighbors was afraid of snakes so he had every tree removed from their half acre wooded lot.

Daisy:

If I may be so bold, based upon your comments, I believe you're trying to resolve a left over festering conflict with your ex-step mother with a contractor instead of a therapist. I owe my 30-year success as a contractor to my ability to immediately sniff out these situations and I'm really good at it.

You may consider my comments "snark", but I have an obligation to posters and readers to call 'em as I see 'em unapologetically. Good luck.