I always suggest that if a person is serious about doing anything with a transmission - you need to go to your nearest 'Pick-n-Pull' and get one exactly like the one in your truck. Then get a transmission rebuild kit, making sure you get ALL the new modification parts to beef it up (listed above), so it will last as long as you own the truck. You will need a long table to take each part out and keep them in order to go back in the same sequence. You can take your time to do the job right. There are dozens of articles and videos to help you every step of the way.
Then swap out the transmissions. The switch takes about 4 hours with a decent transmission jack, or an adapter. It is quick, fairly easy - no mess - no fuss.