Ok, this is where construction instinct comes into play. Never mind "what THEY want". We all "WANT" things. But we have to be realistic. And as professionals it's our job to know what the heck we're doing and make sound decisions REGARDLESS of what the customer "WANTS". And sometimes this means we risk losing the sale. The rest of the wall is easy. So lets set that issue aside. Its the wall by the porch that is challenging. So this wall is going to dictate everything. #1. As I said, I would not cut this porch. We do a lot of concrete demo work on a weekly basis, you'd be amazed at how that slab is probably supported. You could be opening a can of worms. I would let someone else take the risk and screw up their porch before I take on that liability. #2. Wood walls is not the end of the world. In this case, a wood wall is going to be far easier than block. Easier = LESS MONEY. Less money = SALE #3. People want instant gratification. We live in a cell phone app age. The owners probably do not have any idea that something IS supporting THAT slab. They probably thing it's simply sitting on soil. Well - I'm betting there is a 4-8 inch VOID under the slab. So its your job to educate the home owner of potential complications.