There's a few issues with what you're asking about. With the torque tbe drive, there's no "swapping innards" to make it fit modern parts, they're pretty much stock only. Since you're wanting to run a TH350, you can eliminate the torque tube altogether. An easy fix for the rearend, besides swapping it out, would be to use a '55-'62 3rd member and weld up the pivots on the spring mounts. Those come in 3.90 (common) 4.10, and 3.38 gears. The 3.38 is also available in an aftermarket gearset.
On the steering, the S-10 parts won't work. They're 2 completely different styles of steering linkage, with the '53 having a 1 peice solid tire rod, the S-10 having a paralellogram style. Best bet would be to use a tie rod conversion kit and new tie rod from one of the parts suppliers, and perhaps a power steering conversion kit as well, since you do not have the box. I've been seeing that the Toyota box works very well, and can be fit into the stock location. You might do a search on thet for more information.
