There is no argument, both are overpowered, both Dozers are OP and should be nerfed and 76mm stock would be OP.
It is an argument as long as the facts leading to the argument exist. Okay lets pretend it doesn't exist, so that you don't have to apologize for beeing rude without reason. Being a top30 player and having a greater range comes with the responsibility to be more of a paragon, but that are just my two cents as a lower ranked player.
So back to topic: I do think that Calliope + 76mm "blobs" will be countered by JPIV, STuG or Panther play, while Jackson doesn't get countered by them. So there is a downside to the AI value of the 76mm (if compared to M36).
So yeah to conclude, thats the thing about decision making, all choices come with a downside. But atm there is just no decison making at USF nondoc T4 tank roster. You need AI, go for M4A3, you need AT go for Jackson...
The thing is, 76mm have universal shells, unlike the 75mm, and have crazy rof with radio net.
Both is not true.
Radio net isn't as potent as you said because it is bugged and gives the bonus only once. Yeah I do think a blob of vet1 76mm Shermans could be really strong if it would work correctly but that would be true for normal Shermans or E8s too.
Their shells aren't really more universal than the shells of a normal M4A3 as you said. Their shells are identically versus infantry and just have some penetration more. Same penetration at close distance, 10 penetration more at medium distance and 20 at long distance. At long, where the difference is the greatest, this is 66% penetration in comparison to 55% of M4A3 versus a regular Ostheer PZIV. Your shells will still bounce on a regulary basis. The biggest difference is that they shoot about 1,5 seconds faster of course. The shells itself are pretty similar, so either both are universal or none of them. If you want to go for high penetration you have to switch like the M4A3 switches for HE, but your main cannon loose its AI value by doing so and the switch takes roughly about 6 seconds if I remind correctly.
A 76mm is more expensive of course to make up for better RoF and slightly better penetration with standard shell.