I would think a better tank to introduce would be the M4A-3 E8 (Easy 8) and I do believe someone else metnioned. It was a upgunned sherman but retained the shermans speed and maintainability. I would fit in well between the panzer and the tiger/firefly and I don't think it would require a perk. Spces below:
Weight : 33.7 ton
Dimensions: 7.54 x 2.99 x 3.00 mt
Armor (max) : 108 mm (4.25 inches)
Primary armament : 1x76 mm gun
Secondary armament : n1x .50 MG + 2x .30 MG
Crew : 5
Engine : liquid-cooled V-8 Ford
Fuel : 80 octane gasoline (168 gallons)
Engine oil : 32 quarts
Horsepower : 500 (gross) 450(net)
Range : 160 km
Speed (max - route) : 42 km/hr
Maximum Grade : 60 per cent
Maximum Trench : 2.13 mt
Maximum Vertical Wall : 0.60 mt
Maximum Fording Depth : 0.91 mt
ARMOR
Type : Turret, cast homogeneous steel; Hull, rolled and cast homogeneous steel; Welded assembly
Hull Thickness Actual Angle w/vertical
Front, upper 2.5 inches 47 degrees
Front, lower 4.25 to 2.0 inches 0 to 56 degrees
Sides 1.5 inches 0 degrees
Rear 1.5 inches 10 to 22 degrees
Top 0.75 inches 83 to 90 degrees
Floor, front 1.0 inches 90 degrees
Floor, rear 0.5 inches 90 degrees
Turret Thickness
Actual Angle w/vertical
Gun shield 3.5 inches 0 degrees
Front 2.5 inches 40 to 45 degrees
Sides 2.5 inches 0 to 13 degrees
Rear 2.5 inches 0 degrees
Top 1.0 inches 90 degrees
Out,
BigKev