The first problem would be to recognise that you are in a spin when IMC as opposed to a spiral dive (spin - low, possibly fluctuating IAS, spiral dive - high and possibly increasing IAS).
For an unusual position recovery, IMC, not spinning - The TI is affected by g so:
Speed / g / Roll / Pitch
Speed - Low or decreasing - select full power, high or increasing - select Idle power
G - unload (to give a reasonably correct TI reading
Roll - opposite to TI. As TI comes off the stops, centralise ailerons
Pitch - Opposite to Altimeter trend - as height change slows or stops, neutralise elevator.
You will be completely straight and level but fairly close. Disregard AH etc as gyros will probably have toppled., revert to limited panel then select cruise power and tweak roll and pitch to straight and level on limited panel.
If IAS is low and you suspect you are spinning you are in a stalled condition.
Power to idle.
Full opposite rudder to TI
Stick centrally forward until spin stops (TI will come off the stops).
Immediately centralise controls to prevent going in opposite direction.
Go straight into IMC UP recovery Speed / g / roll / pitch