I think a few small global buffs would be best. A small HP buff. A small range buff. A small visibility buff. A small accuracy buff. And a slight cost increase perhaps.
I definitely think it can use a range buff. For instance, when facing off against a panther it has 0 advantages that it can exploit. I really don't know why it doesn't have the same global 60 range that almost all tank destroyer units have.
I don't care if they make it cost more. I rather have something that works vs. something that's cheap.