Merry Christmas!
X2 on Steve C’s post.
Lifter face oiling is only on solid lifters. Hydrualic lifters with the oiling mod have a small groove the outside of the lifter. If there is a face oiling option on a hyd lifter I have not heard of it. As cool as it would be, unfortunately, face oiling effects the hyd lifters function to much. A lot more $$$ for EMD drilling thru the face versus a groove on the outside. Outside groove usually adds $20-$30 or so, may not help much, certainly won’t hurt. More oil should be directly on the face of the lobe.
Johnson R lifter are not variable duration, not much anyway. They just have a slightly higher bleed down rate than stock so they do not pump up at high rpm. You could run them, but really do not need them unless your planning on running extended periods past 6000 rpm.
Other members have said the HS rockers fit under the stock valve covers using the 5/16 thick gaskets. It is tight. I ran crane 1.65 under stock valve covers with a solid roller cam, took some work to do that.
The 703 really does not have much more rpm potential than a 702. It has more overlap and more lift. But the intake closing and the exhaust opening are within a couple degrees of each other between those two cams. 703 will make more hp than a 702, but at about the same peak rpm. A couple hundred rpm higher for the 703 over the 702 would be about it. It will be a beast in the midrange though in a 455. At 5700 it will sound like the 455 with the 703 is going to come thru the hood.
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