Yeah. It can be done by selling all buildings, but costs lots of tiberium and power. Tiberium can be provided from other bases, but power is around 12G difference per building on sell vs new 65 level. In simple average calculation, it will be around 408G power for 34*65 level buildings (he has now, plus 6*53-57 level buildings). Around 500G power can be saved from leveling 6 buildings to only 54-57 level. So, yes, it can be done in this way. Nice to get into this and learn how to survive fast.
Anyway tokenting, thnx for answer.