I am trying to collect all the bits necessary to convert my Revox B77 MkII 2 Track standard into a HS. Not worried about the face or anything like that. So far, I have acquired a 1.177.233 Record Amplifier board, and a 1.021.302 HS Motor assembly. I believe, 1.177.250 Reproduce amplifier, needs to have R1, R9, R17, and R22 (Left) and R27, R30, R42, and R43 (Right) values changed to make it the same as a 1.177.253. (Section 7/53 & 57 In Circuit Diagrams) 1.177.135 Tape Tension Switch, Needs R3, R4, R5, and R6 values changed to make it the same as a 1.177.137.(Section 7/16 In Circuit Diagrams) Both Std and HS use the 1.177.325 Speed Control. I am still scouring the schematics. I am sure I've missed something. Has anyone done this?