VVTI 1.3 Engine will be expensive around 90k for the engine. Plus if you getting wiring done from local mechanics than it will be a tough job getting each and everything work.
I did 5AFE Swap into my Corolla 88. 5AFE is a 1.5 16Valve Dohc engine. The good thing about this engine is its economical (Gives around 190km on CNG Local) and also powerful.
5AFE will cost you 65000 Rs.
More details see this thread.