I'm setting up my SimBrief aircraft profile for the IXEG 733. SimBrief has an aircraft template for the Boeing 737-300, but lets you adjust the OEW, MZFW, MTOW, MLW and fuel capacity to match your actual aircraft configuration.
My usual procedure is to check X-Plane's Weight & Fuel configuration menu for the aircraft's empty weight (OEW), maximum fuel TOTAL value (fuel capacity), and maximum allowable weight (maximum ramp weight or equivalent), and then complete these values using official data from the manufacturer.
In this case, I also used IXEG's preflight menu as an additional source for OEW and fuel capacity (basically matches X-Plane's weight & fuel menu). I'm using Boeing's "737, Airplane Characteristics for Airport Planning" (D6-58325-6), section 2.1.6 (general characteristics, model 737-300) as the manufacturer reference.
http://imgur.com/ysRGN62 http://imgur.com/tUanVxx
W&F. IXEG
Fuel 35,462 35,586
OEW 72,380 72,392
Ramp 139,374 N.A.
The Boeing document has 6 weight variants for the 737-200, 3 of which are applicable to the CFM56-3B1 engine (20K thrust, as shown on the FMC IDENT page), but none of them are a clear match for this 737.
http://www.boeing.ch/assets/pdf/commercial/airports/acaps/737.pdf http://imgur.com/8spPtLx
The first (left most) one has a matching fuel capacity (35,584) but the maximum taxi weight seems quite low (125,000 vs. almost 140K of max allowable weight in X-Plane), as does the OEW (69,400). The third (rightmost) one has more likely values for taxi (135,500) and OEW (72,540), but an increased fuel capacity compared to the IXEG 733 (41,011).
I'm leaning towards the third weight variant without the additional fuel tanks, but I'd rather ask for feedback from the developers just to be sure.
Regards,
Tim