It seems you covered two 'causes' of redshift in this thread - gravitational and cosmological.

The first is well observed, in a variety of environments, and the data match the GR predictions (within the error bars).

What is the (quantitative) size of this gravitational redshift, in the ISU/EEP idea?

The second can be written, in shorthand, as 'the Hubble relationship'. It too is well constrained, now out to z~6, and includes data which lead to 'dark energy'.

What is the (quantitative) size of this cosmological redshift, in the ISU/EEP idea?

How do the two relate to each, quantitatively, in the ISU/EEP idea?

There is at least one other gravity-photon effect that is well constrained by observation (and which is also predicted by GR): the Shapiro time delay.

How does the ISU/EEP idea account for this, quantitatively?