google jdm motors and check out websites prices. it is always best to see the motor in person before you but it. so try to find a shop locally. a s14 sr adv price is $2500 and figure around a $1000 on top of the motor just to get it running in your car. and there are write ups on how to use a ka trans on a sr. it involves swapping the bell housing like this one
zerothread/278158
the search function on the forum and google will be you best friend because there are thousands of threads just like yours