If it were me, I don't think I'd even buy a bigger saw for the small amount of use it'll get. Are there any "pros" in your area, that do this for a living? It would be worth it to approach one of those guys and ask what they'd charge you to buck up a couple of stems. The rest you can cut yourself if you haven't already.
If they work for somebody else, e.g. a company, most guys will do a little work on the side for cash, especially something like this.
Since you're not going to be doing this much at all, having a new big saw sitting around doesn't make much sense.
Any local rental places with bigger saws? Anything that's 60 cc or bigger will run a 24" bar, but you'll have to go slow since it won't pull the extra teeth very well at a normal cutting pace. We had a 262XP that I'd try it with, but the rakers would need to be pretty high to get some of the load off the saw.
It's too bad you're not close to me, I'd drive 100 miles for a chance to really let the 044 chew on a tree that size
What do you have for machinery to deal with the blocks? There's a better than even chance you'll jam the saw a few times unless the stem is die straight. Something that big is hard to deal with when that happens, it really doesn't want to move without serious encouragement.
edit: I noticed after I posted that you had already looked into getting someone else to cut them, I wasn't sure if you'd exhausted all avenues yet. Might be worth posting a want ad for someone with a bigger saw to cut it for you. I know a few guys from a chainsaw forum that would help you out, but none are in Tennessee.
Sean