First, read everything you can find on TBH. Personally, I would use the "weak" colony for best results.
If you want to be able to use your Lang frames, build a Tanzanian type TBH using the width and depth dimensions of a Lang for the best interchangeability. Then during a good flow, remove all the frames from the Lang. Put them in the TBH in the same order as they were in the Lang, except put 2-3 empty Top Bars toward the front of the hive (front entrances have worked better me.) Remove the empty Lang hive and position the TBH in that same location. As your brood hatches and they build comb on your new bars, the colony will tend to move their brood operations forward. Then just keep adding bars towards the front, pushing the old Lang frames rearward. Eventually, the bees will abandon those Lang frames. As they do, you can remove those empty Lang frames with comb to use in your other Lang hive manipulations.
I'm sure there will be a lot of good advice coming your way on this question. Another interesting note - I've had it work in reverse trying to colonize a Lang!
If you want to be able to use your Lang frames, build a Tanzanian type TBH using the width and depth dimensions of a Lang for the best interchangeability. Then during a good flow, remove all the frames from the Lang. Put them in the TBH in the same order as they were in the Lang, except put 2-3 empty Top Bars toward the front of the hive (front entrances have worked better me.) Remove the empty Lang hive and position the TBH in that same location. As your brood hatches and they build comb on your new bars, the colony will tend to move their brood operations forward. Then just keep adding bars towards the front, pushing the old Lang frames rearward. Eventually, the bees will abandon those Lang frames. As they do, you can remove those empty Lang frames with comb to use in your other Lang hive manipulations.
I'm sure there will be a lot of good advice coming your way on this question. Another interesting note - I've had it work in reverse trying to colonize a Lang!
