Well, I think this is all settled and I have a few solid leads on the 6.5HP Duraforce Lawn Boys. This honestly turned out better than I could have hoped. I do like the 80s/90s bottom exhaust with Tecumseh engines like I grew up using(and have mowed a lot of grass with) but did have a Duraforce at one point and it worked fine.
Looking forward to getting back into mowing with these engines I like so much. My wife is a bit hesitant about me buying something older, but I made the counter argument that with as much as-in general-I hate the task of mowing, using something that's both objectively better than what we have now(more powerful, especially for when the grass gets a bit thick as ours sometimes does in the spring) and, more importantly, if I can actually get a mower I enjoy/want to use it makes the job a lot less arduous.