240sxNINJA wrote:1.) I think I can sell the KA24DE for $800-900 if I'm lucky (w/o the wiring harness)
Only to an idiot. There are plenty of KA24DE's around with far less than 90k miles going for under or around $500, including the wiring harness and transmission.
240sxNINJA wrote:2.) Use the money from the DE to buy an SR20DET or RB20DET for the old S13
money from DE + lots and lots more cash
240sxNINJA wrote:4.) Wait for the wiring harness, put the DE in and sell it for $3100 and buy an S14 (I've got more cash in the bank but the extra $3100 would definitly help)
This is probably the best way to get your money out of your car, although it will take patience.
I had an '89 (with a swapped in KA24DE) and now have an S14 (with RB20DET). In my opinion, the first 240sx models were the best and are still the best if they are in good condition. They just feel sportier. Stiffer, more solid handling, lighter, etc., plus the hatchback has more room. Don't get me wrong, I have an S14 now and love it, but it's more of a plush car than the S13 was. The doors are heavier, it does not feel as stiff, and the handling feels a bit less precise.
Having had both, I prefered driving the S13 (comparing KAs to KAs, not talking about my RB20). But the looks of the S14 grow on you, and I now much prefer the curbside appeal of my S14.