Need some help deciding which engine to build...

[itsmetd]

Ok so I have a 1996 240SX (US) with the stock KA24DE in it. I am thinking about buying a SR20DET and building that while its still out of the car and keeping the KA24DE in until it dies. Lately though I have been thinking about restoring the KA and giving her some power. Its got +170,000 miles on it but it still runs strong. Think I should swap it out for the SR20DET or just keep the ol' girl running on the KA and give it some upgrades? BTW I drift so this is where the car is going to be headed. thanks all<(^-^<)