If you're converting, the experience, and the trial and error, of others is the way to save time and money.

I've seen some nice touring bikes with mtb components mixed with road stuff. I've also seen some nice old triple touring bikes make great donor bikes. My mixte build, I hope, will be set up that way, with a triple group from a donor bike.

I've found a couple of problems when converting. One, the FD's are not all that common in 28.6 clamp-on size, or braze-on for that matter. You kind of have to keep on your toes to get one. Two, the FD may/may not work with the crankset. Some FD's, the RSX triple, for example, can cover a 48-26 difference, but cannot cover a 52-30 difference. The increased radius of the larger chainrings (130BCD) over the smaller chainrings (110BCD) can be too great for the FD cage to accommodate.

So, get an FD that fits the tube, and one that works with your choice of crankset. After that, a triple L shifter is a triple, and a long cage RD is a long cage, more sensitive to the cassette than the chain rings.