To double check.. all the bolt stuff was extra info and you aren't trying to solve that, right? You are primarily wondering about the 207K mile transmission.
It'* a matter of time, there is really no nice way to say it. The trans is the weakest link in our cars. Your'* not having an HD diff or output shaft make it slightly weaker in the diff area. Having 207K on it is a good feat for any transmission. Adding power as you have and plan to...you should plan a transmission fund. It'* not a matter of if...it'* a matter of when.
To give you an idea. I didn't plan on going as big as I did.
First I did the maintenance, suspension and brakes
Then I did the trans
Finally I did the engine
Moving fast isn't any good if you can't control it.
Power isn't any good if you can't put it to the ground
OMG.. this car is soooo much fun with everything upgraded.