bro boon, what he asked is can engine from a ff car be fitted to a fr chassis. because he already has an old skool car and he wants to change the engine with newer spec one.
am i right perdanalusuh?
well this could be done actually, provided you are using the engine which is in same family with your current car. what is your car btw if i may ask.
like what you can see in the case of those AE86 guys. originally it is fitted with an engine called 4AGE which is a fuel injected 16 valve 1.6 liter. and AE86s it self are very good as it is in the fr package. and many who owns one have fall in love with the car. but pity when toyota decides that the 86 will be the last corolla to be produced in a fr package. but toyota still wants to develops the mighty 4AGEs as this engined proved to be very interesting. and toyota continues to build the 4AGE but fitted it in a newer, "cheaper than fr" ff chassis. and since then the AE86 owners have fitted their engine bay with a much better, stronger ff based 4AGEs.
and back to your question, yes it can be done but not easily because a lot of things are involved. my suggestion to you is go ahead and do some research first and then decide for yourself wether it's worth it or not.
peace everyone