spacing/breaking with header considered separate from music

[Kieren MacMillan]

Hi all,

I've always wanted Lilypond to have the following (related) abilities:
  1. Consider header and music separately in the spacing/breaking calculations; 
and
  2. Be able to force systems-on-first-page separately from systems-per-page 
[et al.].

Obviously the equivalent behaviour can be accomplished "manually", as I've done 
in my scores through a tedious combination of bookparts, edition-engraver 
injections, etc. I'm just inquiring about whether an automagic solution is 
possible.

In very high-level terms (e.g. "it would touch these general areas of the code; 
difficulty = x/100"), what would be the scope of the work involved to make this 
kind of control possible?

Thanks,
Kieren.