The lobe sepration of the camshaft and the pushrod length are important too...Twisted wedge heads although say works with stock pistons really doesnt as you want the flame kernel dead middle on the piston and non-dished pistons with pistons below deck height cannot achieve such a task.....
Plus on street engines to maximize efficiency you need atleast 10:5:1 compression and the pistons shuld be flush with the deck or a max of .045" out of the hole to help with flame kernel shape too...
A longer stroke and longer rods help alot too because with longer rods and larger stroke it alleviates the thrust stresses on the piston tops that shorter strokes exhibit...A neutral balance helps out heaps too...My 410w idles and runs as smooth as a european made engine....
I built a 347 stroker and put a Vortec V1 and of course it was tuned as anything built out of the normal needs to be tweaked especially the MAF transfer but once everything was tuned and Wideband 02 controller hooked up I was getting 18mpg...........
In the twisted wedge instructions on the last page theres this and a thing most overlook also to mention theres alot more to rocker arms and rocker arm geometry than meets the eye and is more critical than you realize and just as critical as choosing the right LSA for your camshaft based on the setup as theres alot more to choosing a proper camshaft than meets the eye too........,,.
The difference between running pushrods tht are .100" too short is a loss difference of 23hp and 31ftlbs of torque plus the torque dropped off faster with the shorter pushrods too..........
Good Luck