I bought this a while ago and only opened it up this last week, I found the conversion really novel, especially with the twist system for raising the head.

I have had a lot of trouble getting the engine to clip onto the gun, I can see how it's supposed to work, and can get it to sit there but as soon as I pick it up it tends to fall off.

the gun on this one does fit into the shoulder hole, it's a bit tight but it fits, if you look at the post you can tell it has a slight necking near the bottom of the post. so it should fit, just need to be careful and not push it too far or you could damage the shoulder.

overall I really like it, everything clips into place well, I like the head reveal, the gun is OK, and it's my first and only version of this mold.