So far it sounds like most refer to a redline as where the ideal shift point is, not where the point of boom really is. Which of course is smart as 4 jaw mentioned. Since a 4.3 (to my knowledge) is a 350 w/ front 2 cyl missing. I'm gonna assume same bore and stroke. therefore same rods.
when I look at this setup comp cams hydraulic roller, (say 280 duration, 1.5 arm ratio, non roller arm, standard spring) non balance shaft, non computer, .030 overbore, balanced crank rods (heard of a way to do it at home verrrry carrefully), intake port match, polish, 3 stage valve grind(30 40 45) (yeah yeah overboard i know but hey ya only live once) headers (1 5/8), edelbrock 2111 intake (or vortec compatible depending on head), 500 cfm 4bbl, possibly the vortec heads (I still dunno about that one, are they really better?). The card would say 6500 valve float, but a maximium 5000 (still unsure why 2 values there but....).
The next step to ensure safer upper rpm ranges would be springs and rocker arms keeping the same ratio. Knowing this if i did the springs and arms would 6000 or 6500 blow the motor? According to what people have said I'm gonna say no. But I also understand that It may not be the quickest to shift at that rpm as 4 jaw pointed out, however It should be safe to that hit that range by accident or overzealous running at the track once or twice a month.
I know it's kinda broad and I hope I'm gonna get a whole bunch o' answers but ever since I came to this forum I have learned that I know a lot less than I thought, so I'm asking the hard questions, putting some fears at ease about the next motor build up.