The CF-105 Arrow has a niche, albeit, as Canadian, if it's only to soothe some bitter-sweet feelings about the Avro Arrow program

Jokes aside, the IRL plane was designed as a long range interceptor of Soviet bombers during the early Cold War. It was designed with a multipurpose belly-located internal bay, which could have dropped bombs or fire missiles. I don't recall reading the Arrow was designed to be armed with a bullet firing cannon. I suppose in XCF, the Arrow was rebuilt with a cannon mount as well.
The rebuilt Arrow in XCF could show up a little bit earlier, and it's "free" plane. But arming it with cannons only is a bit risky. XCF doesn't have the same large variety of craft weapons like Piratez, so missiles would do.
As for "improvements" to the XCF CF-105 Arrow, I could suggest modifying the missile hard point of the arrow to accept anything about missiles, and all sort of avionic electronic mods, like larger radar or fuel tank.
In my current campaign I took the mothballed Arrow and put in storage. I had two X-Com interceptors operational by the time the Arrow showed up.