Woody, It is not diificult at all to install the trigger pack/sear on the 91. It just needs the .308 ejector(15 second swap) and possible the .308 hammer spring(another 15 seconds). You would have to have a full-auto carrier and it may not be as simple as swapping it out becuase you may have bolt gap(headspcae) issues to deal with. Most of the true HK guns are plug-n-play, but when you use a clone, you sometiomes have to play around with them a bit and get the timing right. You may have noticed the Vector 51 I had at the range Sunday and I was having some "timing" issues with it. It is built on a JLD PTR91 receiver and I am going to have to work on the sear trip lever to get it timed right. No big deal, just takes a little time.
Timing is everything in life too! I am fortunate to have my sons raised and on their own and since I had two of them go in the Marines, I was spared the expense of college. That gives me a little more disposable income to "play" with. I was also lucky enough to have bought most of my NFA stuff 4-5 years ago, and while it was expensive then, it wasn't near as bad as it is now.
Hopefully, I'll make it out to the range on the 31st. Look forward to seeing you there!