99 Civic Engine Swap Question

[waybel]

Hi all,
my son just bought a 99 Civic SI that i beleive needs a new engine.Previous owner changed engines,head,put headers on it .It smokes and every light on the cluster is on lol.Anyways it has a D16Z6 engine in it now and it is suppose to have a D16Y8 .The original tranny is still in there .We have a spare engine/tranny from his old Civic D15B7 .Was wondering if we could put this engine in .If so should we keep the tranny thats in the car now or change both.Would we have to change the CPU also?If this is possible anything else we would have to change?Thanks in advance.
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