Too many factors to decide to swap in a TKX such as do you wanna shift gears, do you have budget for a TKX swap, are you gonna modify the trans tunnel to get the TKX to fit?
A 323 gear, well built 340, and matched torque converter should be a stout runner.
Now, a 727 has around a 2.40:1 first gear ratio and no over drive where as a TKX has around a 2.95:1 first gear ratio and over drive. So a lot more torque multiplication off the line and a lot lower revs on highway. But its pricey and a bit of work to do the swap and its subjective depends on your budget and preferences.