The 64 datsuns had an E#1 series motor with a whopping 60 HP.

Most of these are long gone and rare as rocking horse these days. I bought my 320 (64 bluebird ute) with a J15 fitted which seems to be the most popular as the engine mounts etc line straight up. Not much more power though at 77 HP. My 73 1200 ute's A12 runs rings around the J15 for sure.