I'd just scour knockoff merch until you find one with the correct placement. Official merchandise won't do it, since John's is definitely bootleg. A genuine license would have the front logo slant at a more extreme angle. The centre bar on John's seems to be too narrow too. I figure you have been down these avenues a fair bit already though, yeah?
Sourcing accurately inaccurate bootleg merch, that's an interesting conundrum. Maybe you could redbubble it.
Source: 30 years enjoying Public Enemy.
Substance edit: I can't confirm which of the two possible designs would have been on the back, which we don't see in the movie, however; These PE shirts have the "man in target" logo on the back, there's a round logo and another version which is the same logo inside a square. I'd expect the back logo to be the squared one as this was more usual for the black shirts, but I haven't actually seen the back of the screen used.
I remember this being confirmed in a making of interview, basically it was a costume pun that John both literally and figuratively has a target on his back.
Up to you if this matters or not, but thought I'd mention it.