Ram III
Canadian Pacific Railroads Angus shops in Montreal started 1941 building Valentines and ended the year building Ram tanks.
Valentine was the most reliable of British tanks. Valentine still had room for one more series of upgrades. Canadian production could have been upgraded with sloped cast bows and even larger cast turrets.
However, Ottawa decided that the Canadian Army needed "cruiser" tanks so they ordered Rams based on the reliable American M3 Lee chassis. Ram was the first of the Sherman line with a large diameter turret.
POD General Worthington finally convinced Ottawa that Canadian tanks need big guns, at least 75mm.
Ram 3 runs on the same Canadian dry pin tracks as OTL and shares most drive train components with M4 Sheman production.
The biggest change to the drive train involves laying the Continental R-975 radial engine flat in the hull. This change in engine orientation lays the drive shaft flat on the floor, allowing the turret basket to hang lower in the hull. Ram 3 hull is shallower and lighter than Shermans. If a shallower hull makes sponsons (above tracks) too shallow for ammo stowage ..... fewer ammunition fires and fewer casualties.
If that change restricts ammo stowage too much, apply the Firefly solution of eliminating the bow gun/co-driver and stowing more ammo where he used to sit. The hull is lined with cotton or hemp spall liners.
Will the guy in the back row suggesting "asbestos" please shut up? We can soak cotton or hemp on enough fire retardant to allow crews to exit.
Ram 3 hull is festooned with with toolboxes and brackets for more tool boxes. Most of those brackets are strong enough to hold spare track links or extra armour.
For god's sake, install a pair of tank phones on the transom and teach accompanying infantry how to use them.
Cast bulldozer-mounting-points into the bow.
The fictitious Ram 3 incorporates OTL American 75mm gun. The bolt-on mantlet is longer and pyramidal or conical (think Merkava) to better reflect incoming fire. The longer mantlet allows adjusting trunnions position (fore and aft) to balance the gun (reducing loads on elevation gear). Ram 4 mantlets incorporate optical range-finders.
Ram 3 turret castings are longer with integral bustles. Bustles can accommodate spare track links or baskets to balance the weight of the gun (reducing loads on traverse motors). Ram 3 turrets have plenty of brackets for adding spare parts, toolboxes, etc. cast into the outer surface.
Secondary armament includes a co-axial .30 cal Browning and a .50 cal Browning for AA, smoke mortars, claymores (for discouraging SS tank ambushing fanatics), etc.
In summary, the best tank Canada could make in 1941 would be Ram 3 with an American 75mm gun. The cast turret would look like an M-41 Walker Bulldog. The hull would look like a shallower version of cast M4A1 Sherman Grizzly hull ..... er ..... if you ever got a good look at the tank under all its camouflage, spare parts, tool boxes, track skirts, etc.