I've got a NIB Mopar Performance P4452816 (marked made in Canada, so at least its not some Chinese made POS). Its listed as the correct replacement for either my 318 or a replacement 340, except for the symmetrical bolt pattern; my '71 has that one offset bolt so the pulley would need to be modded or replaced.
The papers that came with it say its "not SEMA approved" but there's no mention of SFI. I assume there shouldn't be any problem with it? Even if I manage to afford the 340 I want, its not going to be a drag engine or overly high-revving...