I don't see any glaring issues. All the R values are what I normally use, and are known working. You can change any and all of them to fit your needs. Did you check the BOM? It has descriptions of most components function and some suggestions for "critical" parts.
As for the gain switch, I can't tell you. I remember a forum member burdij (he has a store called grove audio or something like that, more into DIY synths nowadays) told me once that he always used non-shorting switches and never had an issue. I have always used shorting without any issues. Since you have them done already, just stick them in there and see if there are any issues.
For the zobel and load R check with Sowter. 10K load R seems low. What is the step-up ratio of the trafo, and what opamp are you using? You are going without caps in the signal path, you may want to consider using the servo, and maybe even the bias circuit, to null the offset, if that proves to be a problem.
I have no idea how the access 312 does phantom, but if you follow it exactly I'm sure it will be fine, lots of those PCBs around over the years.
The line balancer is meant for a THAT 1646, the 51R and 10K I believe are used with DRV134 chips. The THAT doesn't use them, check the datasheet, use panasonic bipolars (or other high quality bipolars in those spots).