OzyDuster74 full rebuild and hemi conversion!!

I dont want to tub however i have noticed that the duster has quite a large wheel arch lip and then also the wheel tub doesnt go straight up like in other cars, is there any ways of making the tub a bit more roomy without mini tubbing for example?
We fit a 275/60R15 in the 73 with no problem. 15x8 wheel. Can't remember if it was 4.25 or 4.5 back spacing. It's whatever wheel vinyl question recommended for an A body.