Let's talk 318/349/390 strokers.
I have run both.
A 318/349 build with the 360 crank turned down , factory ported 360 heads and a Comp 282S retro cam (.495
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A 4" 318 / 392 with the same heads and an XS282S cam (.520/.540 - 245/252)
There is absolutely no comparison in the torque produced and the ease of build......go the 392.
349 issues as stated:
1 - Very limited off the shelf piston selection for a 1.65 Comp height slug. (Silvolite 1279 and there's a cast Badger available)
2 - Shaving down a flat top forged slug you run into P-V clearance issues.
3 - Money spent on turning down a 360 crank will buy you a cast 4" crank.
Best MPH with the 349 was 105mph.
Best MPH with the 390 is 112mph.
Carb/intake and gearing was the same (jetting was adjusted)