Well, first off check for frame damage and make sure *all* of that is fixed first (very important for fit). Silvia conversions are neither cheap nor simple. Read up on Sport Compact Car's write up of it a few months back and also look at your online resources such as silvia.org or 240sx.org. Decide what engine your want, you have a choice of the S13 engine (red top; beefier internals and better boost potential, also widely available), S14 (variable cam timing; cool feature, but can only handle so much), S13 black top (actually out of a turbo 180sx) and I think there was an S14 blue top. You can also get an S15 engine, but those are both difficult to find and *very* expensive.

The swap involves the Silvia engine, stock SMIC or you can get a FMIC (need to cut into the stock front bumper or buy aftermarket), the Silvia ECU (usually included with engine), and lengthening the wires to accomodate going from right-hand to left-hand drive. Engine mounts, driveshaft, transmission, etc. all mount up to stock U.S. cars. Bear in mind that the engines cost anywhere from about $2k on up (expect $2,500 to $3k) and labor will range from $1000 to $1500. This doesn't account for beefier internals, FMIC, larger injectors, fuel management (S-AFC, possibly an FPR), revised turbo manifold, turbo downpipe, intercooler piping, catback exhaust, hi-flo catalytic convertor, BOV and a few things I'm forgetting. A well-done swap including upgrades will run you anywhere from $6k-$10k. I hope you've been saving all your nickels and dimes.