How would one model an Ork Warboss with a Kombi-Skorcha?
Since there are no pre-made "Ork Warboss Arm with Kombi-Skorcha" bits, I have decided to do a conversion myself. I will outline the steps I have taken below.


Cut both the Ork Warboss Arm with the Kombi-Rokkit Launcha and a Kombi-Skorcha for Ork Nobs from the sprue and remove any excess plastic and mold lines.
Cut off the front of the Rokkit Launcha, so that the magazine still remains. This way, you can prevent accidental damage to the Warboss Arm.
Cut off the right arm of the Ork nob, so that the hand is still attached to the grip of the Kombi-Skorcha.
Remove parts of the right hand, bit by bit, until only the index finger remains (until about to the knuckle), and the bottom tank of the Skorcha (below the hand). It's recommended to use a small saw to cut through the hand once thin enough, then use the hobby knife to remove the remains of the hand bit by bit.
On the side of the Warboss Arm, remove the remains of the Kombi-Rokkit Launcha bit by bit, until only the hand and the stock above the hand remains.
Cut away the part in front of the "bow" in the stock. It's best to hold the Skorcha in front of the Rokkit Launcha, to ensure not too much is cut away.
Cut part of the Warboss' index finger away. This will be replaced by the index finger still attached to the Kombi-Skorcha.
In order to put the index finger into the proper place, either part of the bottom of the Kombi-Skorcha's stock need to be cut out, or part of the hand of the Warboss need to be removed to create a "slot" in which the weapon slides into. Do either one of these things. I decided to cut part of the hand out.
Once everything is in place, the top of the Skorcha should be a little bit below the old shoulder stock of the Kombi-Rokkit-Launcher. You can either leave it like this to create a "thrown-together-from-parts"-look, sand down the stock or add some greenstuff for a better transition between the shoulder stock and the rest of the gun.
The tank down below will be a little too high to fit below the hand of the Warboss. Carefully bend the plastic down a little bit, so that the tank fits below the hand.
Glue the new Skorcha to the hand and ensure that the stock aligns with the barrel (unless you want the weapon to look slightly bent). Give the glue about an hour to dry enough.
Once the glue is dry, glue the bottom tank to the hand. You can either leave the old grip there and attach the tank to that, or cut the old grip away and attach the tank directly to the bottom of the tank.
Once everything has dried, you can begin to remove the remains of the left Nob hand, still holding the front of the Skorcha. To do this, you can either use a hobby knife to cut the hand away layer by layer, or use a rotary tool to sand the remains away.
Optionally, you can attach some leftover bits from other models (spikes, glyphs, etc.) to cover up the remains of the hand. Such bits can also be bought individually, for several cents per piece.


It should be advised that these instructions worked for me, they don't necessarily need to work for you. It depends on the standards that you set for your models. For example, the index finger looks a bit off, since the angle at which a Nob holds their weapon is different than the angle at which a Warboss holds their weapon. If it must absolutely be perfect, please be prepared to add some greenstuff to relevant parts to ensure the models match your expectations.



Here are some pictures, showing the final result: