Good news/Bad news. I have all the instructions you're looking for, but my camera is w/ my sister-in-law in another state. I also have the color cardstock ‘data cards' that came w/ the models. Maybe we can come to some arrangement where I can photocopy them and mail them to you?
As far as the building of these kits goes, I've got all kinds of advice.
Be sure to paint the interior of the limbs and torso w/ a dark complementary color before you begin construction. (I do it while they are still on the sprue). The interiors of some parts will be visible once the models are constructed, but by then you won't be able to get a brush or airbrush up in there.
If you are going to leave the canopy open on either of them, the interior behind the pilot will be very visible. Hobby Link Japan has some aftermarket/conversion sets that give you details to fill in this area, but I just scratch-build my own. The ‘Gustav' has a spacer piece for the hull that has some molded in details on it, including an SMG (part #b22), but this sits well down behind the pilot seat, and you really can't see it without looking for it. I would include it anyway, as it gives some lateral support to the hull.
The "Gustav' has a ‘T' shaped piece (part #b25) that the ‘hips' attach to. I trim back the flange on the end of this piece (leaving the entire locator pin in place) so that I can assemble the torso, hips and legs separately before putting the whole thing together. This really helps simplify painting.
With both of these kits, you will be able to see light through the finished model if you don't block off the lower torso some how. I cut a piece of black construction paper into the correct shape, then place it in the lower hull. A quick and simple fix.
When attaching the power cables to the hull and legs, I use a drill bit the same size as the coil/spring, and drill all the way into the interior. This gives the cable a firmer attachment point and makes it easier to flex the assembled pieces into the position I want without breaking anything.
Some guys I know fill the limbs w/ Miliput, and then run armature wire down through them so that they can pose the models in a more naturalistic way. With the ‘P.K.A.' you don't really need to do this, but it helps a lot w/ the ‘Gustav'.
If you go to maschinenkrueger.com you can get a lot more advice on how to build these things. Someone there might also have the instructions you need, and be able to post them.
-JC