Additionally to some of the other differences outlined, it is important to note that the M64 Metzger has a race style fully serviceable block, all be it at a price. The Nikasil liners are bolted in and therefore simply removed and replaceable... thus no need to bore it out- replace and it's as good as new. The main benefit other than reliability for these engines was that they were designed to be stripped down and refreshed to new as required by race teams for competition rather than being made as a cast unit intended for a certain lifespan and subsequent trashed (modern engines).
Other differences:
- M64 true dry sump, external tank (as per race cars), 9A1- not dry sump, oil reservoir integrated into block, similar to wet sump
- M64 servicable bottom end- removable cylinder liners etc for stripping down, 9A1- traditional cast block with Lokasil, if rebuilding, it must be bored-out- limited life for this reason esp in racing applications
- M64 proven race reliabilty (24hr enduros etc) and highly tunable- aftermarket tuning exceeding 1000bhp- main recent issue, some GT variants prone to RMS issue. 9A1- no race history therefore no comment. Not much aftermarket tuning available yet so tunability unknown
Whether the new motor will meet or exceed the standards set by the Metzger, only time will tell but it won't be easy.