A mini tub and 3" spring relocation.
Based on the measurements I've taken, with a 68-70 B rear and 1/2" spring offset the 18x9.5's with 285/40/17's I want to run are going to be a just a bit more than 1/4" off the springs and will probably still need a quarter lip trim at my planned ride height.
When I mocked up the 275's on my Duster with the stock springs and rear end, they fit pretty much exactly in the wheel well. No extra anywhere, a 1/4" off the springs and right at the quarter lip. The 1/2" spring relocation should buy me enough to get the 285's, but 10mm = .4" so that's right back to pretty much no extra clearance.
Either that or you'll have to run +2" rear springs and just let the 295's hang out. But lowered and 295's with the stock wheel wells isn't going to work well. Section width on a 295 is like 11.9", stock duster wheel wells are about 12" (at the bottoms!!!). You need at least a 1/4" clearance at the springs and quarters to keep things from rubbing, and that's TIGHT. So, 11.9 + .25 + .25 = 12.4". You might get exactly that if you completely cut the quarter lip off, but then you'll have to weld the quarters and inner fenders with a bead along the edge (not fun). And even then you might not have enough because of factory body tolerances.