trinityamps.com

Hi. I am in the process of designing my own modded amp to build. I'm planning on using a kit from trinity as the base so I figured I could post a question here. It's going to be a modified Valco/Supro model 24. I was thinking of putting a cut control on it in order to allow high frequencies to make it all the way to the power tubes for harmonic content before cutting. I saw there has been a power tube plate to plate high cut control before ala fender deluxe model 26. So I am wondering why would one opt for the phase inverter cut control ala Vox, when you could have it even later in the circuit after the power tubes? Was it simply due to a lack of high voltage capacitors back in the days of vintage amp design?
I appreciate any insight here.