flat6 conversion

[Shadowbug]

dimentions of all the flat 6's are approximatly the same (untill they went liquid cooled) so for your application, newer and larger displacement is better.
there were technical advances throught the years that usually made the newer model engines better than previous years. but it all comes down to the dollar question, how much money do you have. no matter how much money you have to throw at it, with porsche engines, you can always spend more.