By para conversion, do you mean modifying the fixed-butt lower into a para one and swapping the parts on it, or do you just mean swapping the fixed-butt lower for a folding-butt lower and swapping the bolt carrier, top cover, and return springs? Two different things there.
If you get a para lower with the folding stock installed, all you have to do is swap lowers; if the rest of the para lower is stripped, you'll have to swap parts, which as mentioned above will require the stock tool or an expedient so that you can get to the frame lock assembly. You'll need to see if your zero is the same, because it might not be. Obviously, the upper parts are easy to swap. If you want to use a top cover with the nose (which allows for easier field stripping and reassembly), the upper will need to be cut for it. You then sell the fixed-butt parts that you no longer need to make up partially for the cost.
Now, if you want to buy the folding stock separately and convert a fixed-butt lower, then it takes more effort. You have to machine the cuts onto the recoil plate that allow for the rifle halves to be closed with the para top cover in place; the cuts provide clearance for the rivet found at its rear. You also need to remove the receiver tang. If you're using the tangent rear sight, you'll need to either modify the hinge block for the stock so that it will fit with that rear sight installed (like on the SA contract folders) or, more easily, replace it with either the para tangent sight (you can swap the base and use all of the other parts from your tangent sight; The Dealer Warehouse sells the bases), the protected two-position sight (has folding apertures that flip from one setting to the other), or the fixed protected sight (sometimes called the "Holland" sight). DSA also has the A2-style sight that is only windage adjustable that works. There's also an HK-style drum sight out there that should be compatible.