Yes and no. If you rebuilt it with a proper 38mm motor mount (get some proper wood centering rings), figured out a way to strengthen the fins (probably replace them with glassed plywood or all-fiberglass fins), strengthen the body tubes (a number of methods have been suggested for this already), and get some longer couplers to prevent wiggle, it would probably hold together with a J270 or similar. Then you just have to figure out recovery from an apogee of in the 5-6k' range, which isn't trivial (I'm assuming you'll probably end up with something that weighs in the 1.5 kg neighborhood empty). You'll have to either use a JLCR or modify it for dual deploy, and you'll almost certainly want a tracker. At that point, I'm not sure it would be worth it for a cert flight. You'll probably end up spending just as much money on the project as you would if you had gotten a 4" kit and gone from there, and what you'd end up with would only somewhat resemble the original kit you started with. (I'm doing a somewhat similar project with an Estes Scion kit I got back when they were super cheap, and at this point the only things that haven't been swapped out for something beefier are the fins, which I'm fiberglassing)