There can be many reason for stepping up on better parts, when you do testing and see no gain or loss on some parts there is no real reason to step up to the bigger, heavier, thicker more expensive parts. Have you tried Mantons series five 3x8x.142 wall pushrods? If not. you should
As far as the 7/16 single and double tapered pushrods and the larger 1/2 and 9/16 diameter Manton pushrods they are heads and shoulder above anything Smith Bros makes.
My last S/P stroker 400 block had Manton single taper 7/16 to 3/8 .167 wall ball and ball pushrods for the 1.55 ratio paired shaft Jesel rocker arms, those pushrods worked very well with 880 lbs. over the nose up to 7800 RPM, it had 325 lbs seat pressure. That motor turned over, once I got it spinning with a breaker bar, with the plugs out so easy I couldn't believe it
My new NOS B1 headed aluminum motor will get a set of them also with the 1.72 ratio Jesels rockers that are on them, 325 to 350 Lb. seat pressures and 850 to 880 lbs. open. I may end up taking them back apart and try swapping the inners around with other outers to try them closer together on the pressure, + or - 10 lbs. instead of 30 lbs. like they are now.