If you're in North Jersey, like bad 408 said, there's some shops out on Long Island. Couple of corvette shops out there last I heard. SK-Speed is pretty good, I went up there to buy long tubes from Mike. They're pretty good with LS and SBC/BBC builds.
If you're down in Southern Jersey there's Race Proven Motorsports on the DE/PA border, not too far from the turnpike. There's always LS stuff in and out of their shop.
Just depends on where you're at and how far you're willing to take the car.
__________________ 2002 SOM A4 Z-28: Turbo cam, FAST 92, Bolt-On's, 4000 Stall, HorsePowerAddicts tuned
413 rwhp / 368 rwtq
12.01 @ 111.0 mph...Bolt-On's (cam times soon)
what are you swapping?
My friend is almost done with his LS2 in M coupe swap. Rogue Performance in NJ is a bimmer shop and they helped with some aspects, and so did Hot Rod Hotel (in NY hudson valley).
Charles from Sick Speed Performance helped me with my LS1 RX7.
I know Cartek Racing in Garwood NJ (www.cartek.net) has tuned MANY LSx swapped vehicles (Mustangs, BMWs, RX7s, S10 trucks etc.) but not sure if they get involved with the actual swaps themselves.
But once you're done putting it all together they are definitely the guys to go to for the final dyno tuning/programming.