I have a 1990 240SX with a KA24E in it, 190,000 on the body. I want to swap in either a KA24DE or an SR20DET, it has an automatic transmission, would this stay or be rebuilt, or completely swapped for a 5 speed setup? I wouldn't mind, please advise shop-owners... I got cash in hand to get this done. Post Price (total) and timeframe.