Your t-45 is rated to handle 365ft-lbs which is pretty impressive for what it is, a stock mustang cobra or f-body t-56 is 440, a tko500 is rated at 500, the tko600 is rated at 650 and the viper spec t-56 (magnum)/Tremec 6060 is 750. You can figure on a 20% over-engineering cushion for each of them.
You have 444 ft-lbs of torque at the wheels, that comes out to roughly 525 ft-lbs at the flywheel assuming a 15% loss from flywheel to tires. To put that in perspective, most Ferrari and Lambo engines don't have torque levels that high.
Not that your max torque is relatively important anyhow, what really matters is how much sustained torque you can put through your tires to the ground, because that is what the tranny is really loaded with. With 265 tires I would say it's a safe bet you are somewhere beyond the rated capacity of your stock t-45. You could maybe get by with your current tires for a while, but I wouldn't invest in a rebuild or a new t-45 for it.
Breaking stock trannies is going to become an all too familiar thing at your power levels. If you go to the track and throw slicks on, or even drag radials, it will be a toss up as to what you break first, your tranny, or your rear end.....assuming you don't vape your clutch first.
This is not a cheap hobby, you have to pay to play. The most economical way is doing it right the first time and making sure you leave yourself room to grow.
Can you beef up a t-45 to handle your power levels, maybe. Would I want to try and prove it....absolutely not. Your engine at this point is extreme high performance, you need a proper tranny to back it up. A stock tranny will not stand up to the loads for very long.
This is your build, so do it the way you see fit. All I am offering is a perspective on what has been done and either worked or failed. In any case have fun, because that's what hobbies are for.