It doesn't take much. Use the "short" type L transmission and a Datsun 1200 or 1974 B210 automatic driveline. Then you just fab up engine mounts, exhaust and throttle cable. The tricky part is getting the right engine sump, you may or may not need to notch the crossmember.

But since an L16 can break the 1200 differential, swap in a 1975-1978 rear axle assembly and use a 1975-1978 automatic driveline. B210 and B110 axle assemblies swap coupe-for-coupe and sedan-for-sedan but get the spring pads and shock mounts to match.

For more details and lots of photos see our Tech wiki: L-series Engine Swap