you can punch out the cases to accept the larger c85/0-200 cylinders and install through bolts. The longer stroke C85 crank drops right in. Probably wont stay together long though. You can also install the A-80 pistons. and put a short prop on it to get the rps. (A80's tend to run hot and consume oil) The A-75 mods would be the best thing to do and just use a long flat prop that allows 2300 rpm static and you can run it at 2300+ all day long with no problems.
you can punch out the cases to accept the larger c85/0-200 cylinders and install through bolts. The longer stroke C85 crank drops right in. Probably wont stay together long though. You can also install the A-80 pistons. and put a short prop on it to get the rps. (A80's tend to run hot and consume oil) The A-75 mods would be the best thing to do and just use a long flat prop that allows 2300 rpm static and you can run it at 2300+ all day long with no problems.
Jason-
C-85, C-75, and A-65 crank are the same. 85 and 65 crank have a 3-5/8 stroke while the C-90 and 0-200 have a 3-7/8" stroke. The front thrust bearing area on the case is different for the C-85 Vs. the C-90.
Your best bet would be to find a "C" series case and put the C90 parts in it with C85 pistons.
Your most economical option would be to buy the C-85-12 engine that is on barnstormers right now for $4200 and go fly.
I was recommending the 85 crank because it is stronger than the A65 crank. A long stroke 0-200 crank will fit in the 65 case also. I have seen it done, but would not recommend it. I wouldn't waste my time building a monster A65. The A75 upgrade is fine but otherwise get a C90.