1966 valiant rim width with spacers

Hey guys.

every post is somewhat helpful but always specific to that posters rear end, ride height, use case etc.
So I though I would dig into the knowledge bank here.
I’ve got a 4 door 1966 valiant. 7.25 rear end
Front has disk brake swap in progress. To match bolt pattern I did the 1” wheel adaptor in the rear. I have measured 6.5” from face of the spacer to the leaf and only 1.5” from the face of the spacer to fender lip. I could roll the fender and get maybe another 1/4 inch or so.
What I wanted to do is stuff 15x8 With 5.5” backspace in the rear and 15x7” with 4 or 4.5 backspace in the front
I am now thinking this isn’t doable given the overall space is 8” and looking for input as far as width goes in the rear.
To help, no I don’t want to shift the springs over! Looking at some jegs wheels currently but might have to look elsewhere.
Thanks for the help

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