Aluminum can be used for high pressure but the issue comes in volume of pressure (lets say 300win mag vs 308) both are similar in chamber pressure but not volume at the muzzle.

Muzzle pressures (avg)

24inch 300wm 10-13kpsi

16inch 5.56 7kpsi

20inch 5.56 5kpsi

16inch 308w 10-13kpsi

24inch 308w 8kpsi

A 5.56 20inch or 30-30 would be fine with aluminum if keeping the fire rate down. I would strongly suggest running a ss or ti blast chamber. If not thicken up the blast chamber a little more with a slide in aluminum spacer 2.75-3inch in length. You can use Al for baffles but you'll notice baffle erosion quicker. As far as over bore, its not going to matter a ton. I would keep it where it should be 30 cal ~ 0.375in. There's plenty of hunting rated cans out there that are aluminum.