Had the same question as well - I've been following Chris' 69 LT4 build on FB and from his feedback no notching of the DSE frame is necessary when running ac and that the ultimate headers do work fine. It should be close to being done and it looks to be dry sumped as well.
Mark I know as well is in the process with Super Chevy mag on his 69 LT4 patina'd (gordon copied build - lol) no updates as of yet.
Per the link below, " If using the Chevrolet Performance engine
control kit, a pulse width modulation capable fuel pump that delivers 500 kPa (72psi) at 45 gallons per hour is required. If not
using the Chevrolet Performance engine control system, then a fuel pump and a regulator that delivers 500kPa (72psi) with 45
gallons per hour of flow must be used."
Cooling the motor is my particular worry and await other finished installs to see how they've managed the cooling component. Mark has certainly solved this problem and I look to his last few builds for reference.