Terminating bidirectional data lines and clock for memory-mapped devices
I've only done external SDRAM on NXP LPC54648 which can go up to 100Mhz on the external memory interface.  On their eval board they only used series termination on the eval board.  So when I did my board, I stuck with that.
With the cpu and ram about 1.5cm apart, it works great.

For your double termination (data lines) I would recommend using half the resistor value as you do for the single terminations (address lines).

From Dr. Howard Johnsons web site:
Bi-Directional Termination


  [XCVR  A]--[resistor B]--[C--long line--D]--[resistor E]--[XCVR F]
  From transceiver A, the signal passes first through series terminating
  resistor B, and then to the left end (C) of a long line. The long line
  runs from C to D.
  
  From the right end (D) of the long line, the signal goes through
  another series terminating resistor E, and from there into transceiver
  F.
  
  Resistor B, plus the natural output impedance of driver A when it is
  engaged and transmitting, should equal the Z0 of the line.
  
  Resistor E, plus the natural output impedance of driver F when it is
  engaged and transmitting, should equal the Z0 of the line.
  
  When driver A is working, driver F should be in the tri-state
  (open-circuited) condition. This provides a normal series-terminated
  configuration when A is driving.
  
  When driver F is working, driver A should be in the tri-state
  (open-circuited) condition. Now the line is source-terminated at F.
  
  The only peculiar thing you will notice about this setup is that the
  rise time at the receiving device may be somewhat degraded, and a
  little delayed, from the normal situation you would expect in a series
  terminated line. This is due to the effect of the idle (unused) series
  terminator at each end of the line. The received signal has to go
  through this extra resistor into the receiver. In the process of doing
  so, we get an R-C lowpass filter effect with a time constant equal to:
  
  T(Bidirectional,0-63) = (Z0+Rs)*Cout
  
  Where: 
  Z0 is the line impedance, 
  Rs is the value of series terminator,
  and Cout is the output capacitance of the transceiver when in the
  tri-state (off) condition.