Yeah, sorry - the Criterion is AC-3 only. The laserdisc track needs to be synced, no doubt about it!
As for the MGM logo, tsMuxer enables you to set a new entry point without needing to recode the video. It's surprisingly precise - I'd just sync the PCM to the 4K picture as-is, and then those who are fussy about the logo can trim it when they mux.