It will work fine the port mismatch doesn't matter. When I was younger people always told me it wouldn't work and never ever do it because the fuel will smash into the edge and bla bla bla its all myth. Think of it like the the carb doesn't push the fuel down the intake. The pistons suck it like a vacuum. So even with the lip there the engine is gonna suck it right over the edge. Iv had the same 340 intake on 4 engines 3 of them were 318s 2 of those were 302 heads. On the first one I took a dremal and gasket matched the heads to the 360 gasket the the other 2 I did not and I couldn't tell any difference.