Stepping back abit, since I often have trouble getting time to keep up with this thread:
The key to the transmorgrification spells (instantaneous transformations) seems to be here. I don't think LA is relevant, though. A caster's CR doesn't change because of spells he casts (summonings, buffs, etc.); it shouldn't change because of any spells he casts on himself. If his CR doesn't change, I don't see why his LA should change.
I was thinking about this recently, and I think my approach was fundamentally flawed. Measuring a PC by CR is inherently a bad idea. CR is meant to measure how tough an opponent is for a short, intense combat. Outsiders in particularly routine have long lists of at-will abilities at significant spell level and caster level than we would never allow to our PCs as GMs at equivalent ECL.
Consider if I, as a player of a new 1st level character, could talk a GM into letting me take a feat that would allow me to cast
cure light wounds,
magic missile,
mage armor, and
true strike at will with CL1. My rationale is that by Upper_Krust's system, each of those is worth 0.005 KR, and a feat is worth 0.2 KR, so I'm still underpowering the feat by a factor of 10! But now I can heal my entire party in minutes, armor myself, and have a ranged weapon better than the archer's bow. In fact, for the CLW alone, I'd find that a good choice of feat probably all the way until I hit epic levels. But yet, if I gave those abilities to the CR1 orc the party was going to fight in a dungeon environment, the 1st level party would still trounce him. He'd use two spells or so before dying - big deal. They did only add 0.02 KR to his ability to challenge a party.
This isn't news to anyone reading this, it's related to why
polymorph (and
shapechange) can be so powerful - HD is even worse as a measure of PC power than CR.
So we need an entirely different approach for the transmogrification, and I think the fortify seed line is probably a good place to start. My ascension to lich spell should include increasing Int, Wis, Cha by two, gaining DR, the immunities, etc. This also implies something fun (for me anyway) - that perhaps there is a (comparatively) well-known formula that creates the lich as described in the SRD, but an epic-created lichlike transcendance might be significantly different. If I understand recent discussions correctly, we've moved away from "fortify can't be permanent", or at least made it possible that the lich might set themselves up to be that way for 1000 years and then having to recast the "make me a lich for the next millenia" spell. So what's the fortify factor for no longer aging, anyway.
To be really tough - we could eliminate the polymorph seed based on this realization, and say that a polymorph is really an extensive fortification based on the ideal conception of another being. In epic terms, the fact that the meat of your soul's incarnation is reshaped is really rather trivial - after all, these are heroes that are routinely hacked up, burnt, bathed in acid, half-disintegrated and then "get better" and returned to exactly the physical forms they were before. Let's face it, since your wizard's player is going to examine hundreds of published creatures for exactly the combination of powers he wants before choosing what to shapechange into, why not skip the middleman and have him choose the powers. You might offer mitigation as a "package deal" for a predefined sub-optimal set of powers that represent a solar, if you want to keep that flavor.
But, sadly, that isn't feasible, is it? It would require us to define every ability in numbers, much like Upper_Krust's system, except this time with an eye towards PC utility over 5 days rather than Challenge over 5 rounds. A monumental undertaking easily greater than the scope of "lets redevelop epic spells for CL20-40".
