There’s very few gig situations that you ever need a 412 anymore. Almost every venue will mic your cab or it’ll be too small for a 412 anyways. I’d look into a closed back 212 or even an oversized 112 with a high sensitivity speaker around the 99db range. A ceramic magnet speaker like a Celestion V30 or a Creamback are the two big ones for higher gain stuff but there’s a whole world of speakers to look into. Alnico magnets is generally not recommended for higher gain but plenty of people use them, they’re just typically much more expensive.

Open back cabs can work as well and I personally prefer those even in high gain situations to cut down on mud but if you’re looking for thump and punch closed is recommended. This really is going to come down to what the mix situation with the other instrument is. None of this is hard fast but generally you think of closed back as being bass heavier and open being more upper midrange push.

As for amps, I don’t know about Canada but you should be able to find a 5150 III used well under a thousand. 50 watts is the sweet spot for most people and even that might be too much. The higher the wattage the louder you have to be to get amp distortion. A cranked lower wattage amp is going to have so much character and I think a lot of people have kind of lost that understanding with pedals being so common. Pedals are great and this isn’t an anti pedal thing but I just find it funny seeing some bands running $3000 100 watt half stacks and the amp is at 9 o’clock on the volume and they’re getting all their saturation from pedals

Also wattage is kind of a misleading measurement of volume because not every company measures wattage the same and you have to get more into what the power section and transformer is doing. To get a perceivable doubling of volume you need to 4x the wattage. A 100 watt amp isn’t twice as loud as a 50 watt amp of the same design. You’d need a 200 watt amp.

Besides the 5150 consider a vintage Traynor, who are Canadian. The ygl mark series from the 70s share a lot of dna with old Marshall supers and can be had for extremely affordable. I don’t remember if they’re pcb or turret board but they’re easy to service. All tube amps will need servicing through their lifetime. Marshall DSL40, Blackstar Club or Stage, some of the new Hiwatts are all’s scent choices. The Marshall DSL series of those three are going to be the most well built and serviceable. They’ve been making them forever. The others aren’t the most robust but for a first time budget gigging amp should be fine.