My buddy has a BS34 equipped '80 model. He has the straight UNI pods and the Commando exhaust. I doubt there's little, if any, difference in how those filters flow compared to the angled version, and I would think the flow of the Commando pipes is very similar to your MAC. He's one up on the pilots (to a #45) and two up on the mains (to a #137.5). His are the U.S. spec carbs with the fixed needles and #135 air jets, neither of which have been changed. The bike runs very well. He's been riding it like this for several years now so I'm sure he would have mentioned any carb glitches by now.
But, you're up in Canada and could have the Canadian spec BS34s (adjustable needle, possibly 130 air jet and main jet). If so then you may not require quite as big a main. I would still up the pilot one but a #135 main might do instead. That would still be 2 up over a stock Canadian spec 130.
Carb jetting for mods is all about experimenting though. It's best to try a couple successive sizes on the mains at least, to see what works best. The one up on the pilots is usually the norm so you probably don't need to experiment past that there. Only in rare cases, on any of the 650 carb sets, does that need more. On the BS34 mains, one up doesn't seem to do much so I would skip that. Get 2 and 3 sizes over stock and experiment with those.
And one more thing I'll mention, you probably don't need the angled version of that filter, just the normal straight version should fit fine behind the side covers. I'm thinking timbeck has some custom stuff going on and needs the angled ones for clearance or something.