When going from a spreadbore intake to a squarebore carb you need an adaptor like eddy #2732 or you get a vacuum leak along the sides.
And try 12*. My stock 230 six banger luved it. Won't hurt anything except your wallet. You'll get better mileage and save some money.
My tweaked 350 sbc I had with aluminum heads, big crane cam, headers etc used 22* initial. It's the crap gas you buy now.
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