I need intake suggestions for a 318...I have been told that Mopar small block manifolds are usually made for the larger 340/360 ports, and so using them on my 318 would probably do more harm than good. I am currently running the lean burn "302" heads. I kept those heads, what is a suitable intake. Alternatively, if I converted to Magnum heads, which I'm considering, what is a good intake?

Find a good old school LD4B.

Did an ebay search: http://www.ebay.com/itm/Edelbrock-LD4B-A...19e&vxp=mtr
They are a very good manifold. I put one on in place of a performer and the increase was super.

I have a LD4B that I run on 360 heads and on the #302 heads.

I have run many stock cast iron intakes on small port 318 heads with q-jets.

you wont notice any mis-match in the ports with street duty.

tune the q-jet properly and it will make a 318 buzz right up there.

running the stock 88 cast iron intake with a 74 chebby q-jet.mopar throttle lever tac weld on to it on the 91 JY 318 with the voodoo roller cam in the 85 truck now.

biggest thing I had to do moveing it from 360 heads to the #302 heads was adjust the airdoor on the back of the q-jet and pull timeing out of it compaired to what the 360 headed 318 wanted.

IMHO,thats due to the fast burn,swirl port of the closed chamber #302 head.

it flat out rocked with the LD4B and 600 eddy carb,but got 15 mpg and the q-jet is knocking back 19 mpg

the 81 kawasaki kz 550 I just bought gets 65 mpg

SFT is absolutely right on the 4 barrel port mismatch - it doesn't matter that much. If you're looking for that last tenth, it's worth looking at.
I'm using a spreadbore 360 intake on my replacement roller 318 and I was able to port match the 302 heads to the 360 gasket during the porting process. I think I could still take a little off the pushrod pinch, but I'll probably not.

I recently bought a Q-jet for the spreadbore intake but it needs a lot of work.

R.