hey luke, welcome to rollaclub :P
Buying a ke70 is a good way to go cause there's plenty of spare parts out there in case you need anything.
Unfortuantely ke70's didn't come out with a stock 4age. The only thing close to it is the AE71, which is pretty much the same car but with an 4A motor in it. But they are relatively easy to convert to 4age.
The ke70's came out with the stock 4K-C 1.3 litre. They also came out in either 4 or 5 speed manual. Or even automatic. Alot of them don't have a/c or p/s so there is an extra 5hp for you're motor right there :P
Are you planning on having this as a street legal car or race car?
Cause if you wanna be driving it around you'll have to have the back seat staying in and carpet is definitely a must to make to comfort of the car alot nicer.
Anyway there is alot of people on here that can help you out alot more than i can so yea...
good luck