Ok, so I'm thinking ahead here so bear with me here. If I get the Festiva I'm thinking of swapping the engine for a used 4age engine. First, is it possible. Second, would it be worth it, and third how much would it cost.  

hey sorry i'd like to help but idk what your talking about really... what is a Festiva? and a 4age engine?  

Dont use the 4age. Use the motor out of the old Mazda 323. It will fit much easier (same chassis) and it will probably make more power.
Try looking up SCC's project Fastiva. See what they did.  

Ok, The Ford Festiva is a small, RWD 2door car that puts out like 60hp. If you know me I would do almost ANYTHING to get an AE86 (1985-1987 toyota corolla gts), or a 1985-89 Toyota MR2, which have the A-4-G-E motor in it (not pronounced age) which I love. Some people say they are almost indestructable.

does that answer your question?  

I say make a SHOgun out of it... drop the entire drivetrain out of a taurus SHO into the back  

Well said MadMachine. Thank you Chris Titus.

I've seen and heard both 4AGE and A4GE for the same engine, even 86er's refer to it more as the 4AGE.

Festiva is Ford's version of the Geo Metro, only in my opinion, better looking. It was a little econo hatch that makes for an awesome sleeper due to it's ability to accept turbocharged Mazda engines. Jay Leno hired car builder Chris Titus to build up two Festivas, known as the SHOguns, by shoehorning in Ford Taurus SHO V6's in the back of the car and then feeding each engine nitrous. Run a search engine on "Jay Leno SHOGUN" for a view.  

Holy crap, that engine in the Festiva must have made a rocket ship from hell!  Oh, I didnt know that the Festiva was RWD either.  Hows this idea, little bit of a stretch but what about using a 13b engine found in the earlier RX-7s?  Tranny was made for RWD cars, the engine is Mazda and pretty small.  Itll make for a killer sleeper.  

...RWD Festivas?? I've worked on quite a few of those but never saw a RWD. How the hell would you mount the engine longitude wise? The engine bay is 2 feet wide, and no tranny tunnel.

I know guys who've built "Fastivas" and their cars are turbo FWDs.

BTW, go with the Mazda. Ford and Mazda are in bed so everything will be easier.