Over pumping the radiation uses a more pumping power than necessary, but it's usually not a critical flaw on a system that is plumbed primary/secondary. Replacing pumps isn't cheap, and you can buy a lot of electricity for the cost of a new right-sized pump. Getting the boiler-loop rates dialed for a reasonable delta-T across the boiler is of greater importance, but of course the primary & secondary flows do interact. Most systems can run just fine with 1-2gpm flows on the radiation, and it's quite conceivable that your whole house could be served by a single Taco-007 & four zone-valves. (TBD.)
In your length/head approximations be sure to look up and include the additional head or "equivalent length" of all the ells & tees, etc.
The Slantfin tools regularly hit 25%+ higher than measured reality, so if it's coming up at 60K, the real heat load is likely to be something in the 45K range.
Rather than pumping rates on the radiation side, I'd be more concerned about short-cycling a boiler with a min-fire output of ~28-29K in condensing mode on zones with the heat load of most singles zones under 15. Gross mis-matches between zone radiation and min-fire output often prevents systems from being able to run in condensing mode without short-cycling the boiler into an early grave. What's the radiation size/type on that 70' kitchen zone? How about the radiation type/size on each of the other 3 zones, by zone? (I don't recall if you covered this on another thread.)