You say it’s narrow and there are windows in the house that look out into this space. What is your goal for this proposed change? To make it less narrow? To reduce the number of windows?

Are you thinking to remove the entire screened walls with the porch becoming accessible all along its length?

Is the home located in mosquito country?

You won't know until you start, but the bones should be under those finishes. Is the floor concrete slab or wood framed? Usually it's sloped and it's left sloped, but yours looks level, which means something was done to level out. There are probably studs between the windows that will hold up the roof, while you decide where posts can be. It seems like that space would get very hot!

I am sure you could convert it back, but, I would wait a while before I did that. Use it like it is, and see how you like it. A closed in porch is very nice to have, if there are any mosquitos, or flies etc. You may find, if you remove it, that bugs are so bad, you cant use it a good part of the year. With it enclosed, you will be able to use it often. I love sitting on an enclosed porch, sometimes, not so much on an open one.

What is the actual width, and where are you located ( climate, biting insects) and what direction does it face? These will affect whether it’s a good usable space whether open or enclosed and in what seasons.

Av

A very shallow porch is problematic in most situations, since that severely limits furniture arrangement, but also, shallow , open porch or balcony is not usable in wet weather. Whereas, in mild year round temps with few bugs, a breezy open space is good.

I agree you probably need to decide whether house is otherwise great , and this area can be figured out later. You should get experience with the weather & sun patterns and how this area does or does not relate to adjacent rooms, to know what modifications, if any, make spaces more usable.