Thanks guys, I found a rifle local that im going to buy. It is a HK 94 that was converted to an MP5. It has the SEF plastic lower which will be changed out to the 0,1,3,30.
Any recomendations on who to have do the work?
Will this modification risk the value or permanintly damage the sear?
TSCMachine, RDTS, or Urbach all do them for sure. (Please don't send it to Urbach, it may slow him down on my G3K

). I'm not positive, but I wouldn't be surprised if Jayson at Investmentgradefirearms didn't do them as well.
I was about to add one more comment to my previous post - now that I have one, I never, ever, use it in burst mode. With some practice, you can learn to fire 2 round bursts, or 3 round bursts, all the while in full-auto mode. (And by repositioning your trigger finger, even single-fire shots as slowly or quickly as you wish). I'll probably still keep it, but will eventually replace it with an ambi 0-1-Full picto lower. Besides, it's more "correct" since mine is an MP5-N anyways.
And no, it will not devalue the sear in any way. It will not be modified (unless it's one of those odd-ball ones, like the ones where the trip lever and catch are a single piece).