Check if you have a Foam company in your area. I recently reupholstered a love seat and I replaced the foam inserts on the seat cushions. I found a store near my home (Southern Calif.) that has many choices and will custom cut the foam to the size and thickness you want. I wanted something very firm so I ordered the "Q41" (2.8 density, 41 firmness). Prior to inserting the foam into the fabric cover, I sprayed the foam with a special adhesive and wrapped it with 1" thick Dacron batting. To get an online price quote and to learn about various foam types... open the A-1 link below, pick on the Foam link at the top. Next, pick on the square shape. Then, it will ask you to select 1. dimensions you want, 2. how the foam will be used, 3. select foam type.... just below #3 in small print, you will pick on "Click here to learn more about choosing the right foam for you". Here you will learn about various cushion/foam firmness and density and the numerical system used to rate a foam's firmness. It will also have a chart for various foam types and typical uses including mattresses & breakfast nook applications. I noticed that they can send you 10" x 10" samples. What you pay for the samples is applicable to any future order. In my case, I was able to feel all the samples in the store. -Laurie Here is a link that might be useful: A-1 Foam and Fabrics

The english roll arm is designed to be luxuriously deep seated, with a pitched back for comfort.. In fact, 24 inches is quite common. To mess too much with depth, destroys the proportional intent of a classic design. If you want a more upright back, shallower seat depth, select a different style altogether....or add toss pillows: )

IMO you still need to add knees sticking past the sofa and then see how much walk space you have . IMO a porch can be a bit tighter than a LR for walk space but you still need it .I would probably look for something a bit less deep. What are the measurements of the new sofa especailly the depth.I would look for something like this and put it in that back corner it is only 67" along the short side and only 28" deep front to back It is called othello from Wayfair .

Honestly, two dogs and a clutz should consider an IKEA sofa. I am a fan of this one: Reconsider the down filled. I have heard it doesn't like Coke, wine, or coffee. Here are some other suggestions: https://www.thespruce.com/best-slipcovered-sofas-4169654