Specification During Design

I want to undergo my feasibility study on designing 220/132KV RING CIRCUIT SUBSTATION, What are the recommanded specifications on selecting proper four Transformer (T/F) which will fit for interconnection btn two substation circuit 2.For Generating Units and 2 for Power Transformation.What I know some like

T/F SIZE RATINGS

33/132KV sub. 12-15MVA

66KV/11KV sub 40MVA

132KV sub (NR) 40MVA

220KV sub (NR) 60MVA

66/132KV sub ?????

220/132KV sub ??????

66/33KV sub ?????/

220/66KV sub ?????

220/33KV sub ??

For Higher voltage ????

NB:It is necessary to note, NR =NO RING CIRCUIT and sub=substation .These ring ciruit CONNECTION, the opposite transformation is true but hopefuly we will have the same MVA ratings.Lastly some studies were done based upon already installed capacity but justification or commandment is also acceptable.