There have been ppl who have posted up TKO and TKX swaps in this forum. The TKX is slimmer and does not require as much cutting welding to make tunnel wider taller.
If you found someone with 340 and 5 spd you can have then put flywheel, bell housing, starter and do a compression test while you watch. My son bought a 2.4 Honda K engine and we watched all 4 cylinders get compression tested before we handed money over. Engine should have oil in it prior to cranking of course.
Your right a manual trans will appeal to more buyers and boost value. But its a lot more time and money to swap from auto to manual.
I jumped through hoops to modify a 4 spd console shift handle to hook to a 6 spd out through 4 spd top plate. If you dig though my thread you can see pics. A lot of ppl just slide console rearward several inches which is a lot easier then the way I did it.