Having been in the NA scene with my S14 for awhile, I would say go the SR20DE route. I nearly bought the motor below before finally putting DET into it just recently.
Had all sorts of tweaking, Nismo 296 duration cams, extensive head work, Jun bottom end, circa 250PS easily.
If your on a budget, stick it out with the early S13 SR20DE; Pulsar N15 N1 pistons, high lift cams, extensive port work. Nismo N2 4 throttle kits are still popping up used here and there but mind you will have to switch over to airflow less CPU.
Ill be going back to S13 with this sort of build down the road. Totally regret tweaking the S14, just a heavier car and not true to N2 racing routes as the S13 was.