340 intake on 318

Your 318 will like it.
Agreed. Yes there is a port match problem but a stock 318 it doesn't matter. Use the 340 gasket as stated above.
Did the swap way back in 1975 when I spun a rod bearing on my 340 Duster .No money to fix the 340 but a year old 8,000 mile 318 only cost a $100 junk yard price back then.Ran fine for 10 years till rust turned the Duster into dust.