I want to combine 10 acres and 2 homes which includes a inground pool and a building that has a 2 car garage and a game room. I want to sell all of it for $650,000.00. I owe about $350,000.00 on the properties which I want to pay off and take maybe about $200,000.00 on new home and whatever is left in a IRA. If I was to do so, would it hurt me with taxes or is this a dumb idea to begin with?

Your question brings up too many questions; see a tax advisor or possibly a veteran real estate agent (who will want the listing and will jump through hoops for you).
Not your primary residence: capital gains ('gain' you have to calculate from basis, etc.).
Married excusion, 500K, single, 250K.
Ownership/use: owned for at least 5 years, lived in as your primary for at least 2 out of last 5.
And so on.

Combining two properties when only one was your residence will make it more complex, and I doubt that you will get the price you want that way - how many shoppers are looking for 2? And if they are deeded separately, they have to be sold that way.