Thanks again for the comments guys.
I used the Comet tub. The transmission doesn't fit the Comet's trans tunnel well and will push the chassis down, so I trimmed off some of the transmission top until it fit properly. It took a fair bit, but is unnoticeable after final assembly. Also, since the Comet tub is shorter than the T-bolt's, it will leave an open gap between the firewall and interior tub. I had thought about filling it in with some Evergreen, but I decided to leave it as is. With everything painted black, it really isn't that noticeable anyways.