Small block cylinder head specs

Please explain the PM Dart19666 part. I'm not familiar with the names of the springs, PAC & Associated. Yes, the rotators are almost a requirement for a HD engine. It is in a class-B motor home & fairly heavy but the weight is not as much a factor as aero drag. A class b is just a regular maxi-van but w/ a high fiberglass top. Engine is stock bore & crank. All were in good shape w/ only .001 to .0015" taper on the bore. Just a re ring & new bearings. And the timing chain was double row. Replaaced w/ a melling unit. Engine is LA block w/ flat tappet hyd. they didn't start the roller cams until the next year & not in all engines for the 360. Did a 360 LA out of a 1 ton dually a few years ago & it had the roller w/ TBI. Compression is factory but I had the heads milled to make sure they were straight. Probably no more than .010". 3 difgit head casting 596, block casting has no dash # after the 360. Motor has not been replaced. The cam is a regrind from Oregon cams. On cam specs: Best info I can come up w/ shows 2 grinds for that year w/ 360 & 4bbl, single ex. In lift of .372", ex .400", dual ex In & ex .409". my regrind has .400" in & .417 on ex. Shouldh't have any issue w/ spring bind w/ only .008" more on the ex side. Yes, truck, B-350 van. To give it a bit more advantage I am using magnum ex manifolds & increasing the single ex to 3" from the existing 2.5". I trust the original stuff way more than a lot of the aftermarket stuff we are getting now. Chrysler stuff good. I've built a lot of these engines in a similar way that I'm doing this one & have had real good luck, just nervous about using aftermarket valve springs & can't find a direct replacement for the ex w/ rotors.