Definitely keep the G36 intact and build a specific Phono pre. The G36 is worth way more "unmolested".
I love the sound off my G36 and D36, although I'm toying with modding the G36 to 7 1/2 / 15 IPS CCIR.
This means a new capstan and some eq component changes, but quite doable. A thing to watch for on the tube Revox machines is they use different capstans for 50hz vs 60hz .I have 50 Hz ones but the 60Hz ones are in the " unobtanium" class unless you're lucky. I've looked in the past and have never found one.