Well the engines u mentioned are not so economical engines, they are more of performance ones .. the best option i can give u is that i have the original petrol engine form my Celica laying with me .. which would be a bolt on fit in ur car place CNg on it and there u go
... all the economy u can get ...
PM me if u want the engine ..
Rest as far as LSD is concerned here is a small informative video which can explain it better
//youtu.be/http://www.youtube.com/watch?v=lpf2pK-gGKk