In general, you can do it. Just tell them you want the loan and aren't sure what you will do with it yet - may do some improvements or something else. Once it's approved, you can do what you want with it.
We had a house worth $550K (owed $100K on it) and took out a $250K interest only home equity loan and then bought another house with it. We did it so we didn't have to sell our house before buying another. Then we turned around and sold the first home.
Having said that, I don't know how much they will lend you with $70K equity, if that is how much you have.