JEFF B. - As much as I am SO NOT a member of the correct police... I could NOT bring myself to notch the frame on my 72 to fit a K321 in it.
The only words of caution I was given about a small flywheel 14 hp Kohler was to try not to pull it real hard in 90 degree temps. Short bursts of higher load are O-K, just nothing for long periods of time.
LUTHER - My K321 isn't quite stock, but as long as I have it running half throttle it WILL accelerate. And that's the one thing a small flywheel 14 will do. I put the BIG flywheel back on the 12 HP and what was a real nice running 12 HP Kohler became an absolute slug. It would still lug the same as before, not any better, but wouldn't accelerate or pull any more. From everything I've read, you can not tell the difference between a heavy & light flywheel engine on a dyno, they don't make any more or less HP, they accelerate faster (light FW) or slower (heavy FW).
Example would be when breaking the 14 HP Kohler in, was trying to put some load on the engine, yard was damp, couldn't get ANY traction, so finally pulled the 7000 pound FARMALL M I was using as a tow weight into the frt yard and got on the driveway.... was about half throttle in 2nd gear.... both tires spinning, gave the engine full throttle and in a heart beat it was at 3600 RPM, both tires still spinning. A stock K321 Kohler with the stock flywheel would not have accelerated that fast.