haven't seen a zen2 imc which doesn't do 1867 fclk yet... you should be able to get there.
save your 3600 profile load defaults (don't touch ram just yet) and raise fclk to 1900.
if system doesn't post .. try VSoC between 1.00 and 1.15, try smaller steps such as 1.00 1.05 1.10 1.15V.
If non of those will let your system boot, try to adjust VDDG between 0.95 and 1.095V (vddg needs to be lower than vsoc, so you need to adjust and test both values at once.
If no luck just try 1867 and repeat the same steps.
If your system is booting up you can check 2 things before you start to OC your actual ram.
1) Do a 30min stresstest ("Stress cache" only) using Aida64, this will show you if the VSoC is stable.
2) Stream a movie or watch a youtube video at the same time, if there's sound issues then your fclk is not stable. (unfortunately there's no other way to test stability for fclk as of now)
Best of luck

Got myself another 2 (2x8) E-Die Kits on my holidays btw

Hahahaha good for u more e dies to play with. Thanks I will try ur guide