I'm not sure and still trying to find a way around this, but I believe having seperate star base looks for each race is impossible right now. When I did attempt it I always got a crash, it looks like all races are hardcoded to use the ShipCfg file of S0_MilitaryStarbaseXX, so no matter what ship style you set for the race it uses that one when it comes to star bases... I tried creating my own S1_, S2_MilitaryStarbaseXX files, but it crashed when I did that, and worked when I removed them. I could of done something wrong, lord knows on the ST mod we are always hitting things that cause an issue before we get it right. I'm still looking into this one because I think having a different looking starbase for each race would just rock...
BTW I know thats not the actual name of the ShipCFG file, but didn't want to go look it up

If you guys want to mess around with them though all you have to do is go make duplicates of the different ShipCFG files for starbases and rename them with S1_, S2_, infront of it and change the .X File that the Base Hull is pointing towards, let me know if you figure it out! Should be 4 or 5 for each type of Starbase, Research, Cultural, Economic, Military and I think there is one for Mining