looking for unfinished seconds,doors

My 1970 aluminum patio slider is 81" high. The opening is about 81.5. The standard size now appears to be 79.5" and I see that some manfacturers, like Anderson and Jeld-Wen, have an 82" model and custom sizes. I haven't inquired yet about the premium for a custom size but plan to go to Home Depot this week since they are advertising a sale on Jeld-Wen custom orders. Looking for opinions on which way to go. If I go standard size, I'll have to figure out how to fill and cover that 1.5" gap. Custom size would be preferable but I'm concerned that there may be a substantial cost premium. Any thoughts or recommendations?

We are confused on what we should do. Currently there is an old solid wood door that swings into the house. It actually swings right into a stair case which is very dangerous. We don't have a lot of room so we don't really want to have it swing the other way either. So, I purchased a prehung metal 6 panel exterior door and assumed I could just install it the opposite way so the "entry" of the door is into the garage. Well that doesn't really seem to work since the threshold would be inside the house. The current door and frame are completely shot, so we have to replace the whole thing. What kind of door do we buy?