Hi Cory, just wanted to give you my perspective so you can temper expectations and go into offers understanding what to expect. An important thing to understand is that commons and uncommons, for the most part, are considered bulk, especially when using them to trade into an older high value card with a stable price. I believe that you could remove 99% of the commons and uncommons from any relatively new set (last 5ish years) and your expected offer's value wouldn't change in the slightest. There are exceptions, like Fatal Push etc, so I'd say any uncommon that is $2 or less by deckbox's pricing is probably close to bulk in the eyes of the person your offering your collection too.
Secondly, using new or "bulk" rares to trade into the kind of card you're looking for, I'd go into it expecting a 25-30% mark down of value on your end. It's very unlikely you'll find a person who actively wants all the cards you're offering, so at that point they are trading for value. Trying to move 200+ mythic rares, rares, and uncommons that range from $1-$5 is a lot harder than moving one high value card, so it typically needs to be worth it for the person that you are trying to offload stuff too.
Now, I am pretty new to this site, so this experience is more so geared towards local or GP trading, but I think the fundamentals hold and I know I wouldn't want to trade a Force of Will ($110-120) for 110 or 120 $1 rares, if that makes sense.
Looking at your tradelist, you could probably cut everything out below your 50th most valuable card, then look to offer someone it (about $250 in value at that point) at around 160-180 (maybe) for some amount of 10-50 dollar cards that would equal that, then use those to trade into the card you're looking for.
Anyways, I hope that's helpful and best of luck with the search!
I can send pictures of the RoW too if you'd like.