The lineup is fine, you cant fight head on with german tanks though, you need to flank a bit and use your stab to play peekaboom. The 76mm should have no troubles 1 shotting almost everything it fights honestly.
The Jumbos are in a weird spot, I still can do well with the 75mm jumbo but at 5.7 it is a bit overtiered, and you have to be creative in your gameplay with it. I also wouldnt bother taking it out as anything other than a last spawn if you are bottom tier.