What would be a good .67 to buy for a 1/8 scale... by "good", i mean power, reliability, part's availabilty, rebuild cost, etc... just like everything, you get what you (hopefully) pay for !?!
If you want the hottest engines for racing, CMB and MAC are what you would want. If you're just looking to "fun run", Picco would be a good choise as well.
The truth be told the only motors that are currently being built and parts availabilty are the CMB's. If you want to know which one is the latest one being built call Tidewater. There's really not much of a selection out there right now.