[curiouscat]

This may be tangential to your application, but to overproduce a small molecule (and biochemists will call a molecule with MW = 250 a small molecule) you may need to consider the ideas of metabolic control analysis.  Metabolic control analysis looks at the flux through a biochemical pathway, almost from an engineering perspective.  Just doing a very cursory search, I found this:  "Increasing the Flux in Metabolic Pathways: A Metabolic Control Analysis Perspective" by David A. Fell.
BIOTECHNOLOGY AND BIOENGINEERING, VOL. 58, NOS.2&3,APRIL 20/MAY 5, 1998

Thanks @Babcock!

This is *exactly* what I had wanted to do. But I felt totally inadequate regarding the tools needed to model (say) a yeast network. What I'd love to do is to predict, at least order of magnitude, what sort of expression levels I might expect even before I start any experiments.

e.g. FPP goes to squalene and that will be a major drain on the precursor pool. I'd love to model, for example, how much improvement in flux I can get out of blocking squalene synthase. 

I'll read that paper you linked to.

Meanwhile if someone knows of any good tools to do this sort of modelling in I'd love to hear.

[Yggdrasil]

Here's a review that might be useful to take a look at:
http://www.sciencedirect.com/science/article/pii/S0958166913000554

For example, it has a few paragraphs discussing how to optimize tune protein expression levels.