Wow..I'm grateful for the input here!
My truck is a 2wd, regular cab with the 545 trans. 340,000 miles on everything. It has been well serviced though. I do have a cold air kit from K & N. The exhaust is stock to the bed, from there it is a single inlet, dual outlet Flowmaster.
The 6.1 engines I have seen listed here are over $4000. They do come with warranties but I don't know how soon I could do this swap. I've ran into situations where the warranty of something runs out long before the part is ever put into service.
A long stroke rotating assembly is $2300. This takes a 5.7 up close to 400 cubes. That was one of the ideas that I was kicking around.
This truck is used for work...I'm a Carpenter and do a fair amount of commuting. I also use it as my primary driver. I am interested in a modest power increase but not one so much that I start spitting transmission parts. What kind of real world increase can be expected with those JBA headers and a 6.1 cam? I'm keeping the MDS.
I am not against using a 6.1 if I can find one reasonably priced. I'm not going to spend $3500 on a used engine. If that is the going rate, I'll stick with a 5.7.