Interesting that your kit came with two cannon. I still have my invoice from Model Expo in the box.... dated 1984! Forty years ago! And after reading your posts, I decided to take the box down from the shelf and have a peek inside (again). No cannons. No sign of them on the box cover photo, nor in the instructions or plan sheets. So the change to kit contents must have occurred shortly after your kit was produced. I'm trying to remember if my first version of the boat had them or not, and I honestly can't recall. I think I'll follow your example in this case and build my Swift without cannon as well. I thank you for the offer, but maybe it's best you just keep them in case you decide to put them to use in some future model... or you could use them to scratch build a small bulwark model showing a couple of cannon positions and all the associated blocking and tools (if you decide to do that, drop me a line here and I can provide you with photos of a couple of kits I built that could give you an idea of what it might look like). I'm also a kit pack rat. Any surplus materials from any of my builds get tucked away in case I need them in the future... it's always nice to have bits of dowel and various sizes of planking and dimensional stock handy in a variety of materials.
And, exactly like your kit, I see my keel section is warped (bowed out longitudinally) from stem to stern, with about a 1/3" out of line at the centre point... so I've got some straightening to do as well when I tackle mine. Only one double sided sheet of plans, but the written instructions provided in those early kits are far better than what AL provides with their more recent kits. My Red Dragon had very minimalist written instructions and relied heavily on a double sided sheet of photos from which you were supposed to ascertain what the heck you were supposed to do. That said, and off topic, some of their later kits are providing much better instructions, albeit on either CD or via their website in .pdf format. The newer versions of their instructions would remind you very much of doing a LEGO Technic build, if you've ever seen one of those. Literally a "step-by-step" using images to guide you through the build.