You can run much longer rods in a 318 than a 302. Factory heads flow just as good, 318 magnum heads flow better than almost any factory 302 heads even on a smaller bore. I have seen a few tests compareing same heads on a 3.91 and 4.0 bore and the flow is almost identicle even with a 2.02 valve, factory magnum heads flow the exact same on a both bores. Also because of the taller deck a 318 has more room between the banks for better intake desighns. The bigger crank case allows for a 4 inch stroke with out clearancing anything and even a 4.25 with very little clearancing with the right rods, try that in a 302
Personally I like the longest stroke I can fit but I will say that in a drag type engine the stroke does not matter much if you don't mind winding up the smaller motor and finding the right gear and converter, the longer stroke just makes it easier to run the number and is more forgiving of the wrong gear and vert.
The 318 just never came as a performance motor, even the cop motors were a complete joke because of the 7 to one compression, because of that they got a stigma they never could shake. The 4bbl motor only made like 10 more HP than a 2bbl, just adding a 4bbl should have added more than that but they insisted on adding heads that killed the power in the name of emmissions
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how about this one? 318 Poly block bored .125 with the above mentioned 4" crank for 420+cubes and magnum heads etc. Now you have some torque! There is a post on here 
I have seen everywalk of engine out perform another in some shape form or fashion. 383's are considered the "best" because you can build them from the beer can collection out back. Cam it up some a 292 does good on the street and strip its more less a midground of performance and affordability to cruise and not have to carry a can of fuel with you. Drop a matched intake and carb to it as well as a stall. This should add a good enough thump/set you back in the seat for a "street Sleeper" its quick simple and reasonably cheap. Guy ran at George Rays wildcat Dragstrip for years as the 8.0 champ 1/8th mile ran small blocks with that smae setup and 3 on the tree and he was the man to beat. The only thing that would be noticable from the outside is the intake which can be painted to match the block and be harder to tell.
