BK117 A4 modified to B2
LTS 101-750B1 engines (750 HP)
Payload max gross 3350kg up from 3200kg
Max gross with external load 3500kg (up by 300kg)
Improved CAT A performance up to 280kg higher payload
Upgrade kit for A4 to B2 includes
Uprated engines (750 hp)
new T/R blades (improved design)
Increased pitch range of MR blades
Uprated OEI Main gearbox limit (2.5 min limit up from 100% to 125%)
New engine instruments (different limit ranges)
To upgrade from A1 or A3 to B1 the A/C must first be upgraded to A4 model
I believe the A1 and A3 had the 650 HP LTS these had quite a few problems and were often removed for inspection every service. Not a problem now with the 750 it has new GP Turbine Disc (single crystal) stopped cracking problem.
You may find that some A4s have been upgraded with the 750hp engine but have not been upgraded to a B2 because the kit can be quite expensive... I have heard that the torque gauge costs at least 20k US.
There have not been many major airframe mods throughout the range mainly engine mods to upgrade.
So the best bet may be to purchase an A4 and upgrade to B2 for a pretty good performer.
As for PAX you can have 8 in the back and 2 crew for a full load or may other variations of seating as required.
Max hook load is 1500kg but I think you would be lucky to lift about 1100Kg on average.