The advice about 55 horsepower is absolutely true. My PA-15 which is powered by the Lycoming just can't keep up with the essentially identical PA-17 powered by an A-65.
Couple of concerns:
- The front oil seal is almost impossible to find.
- It uses three gaskets between the steel cylinder and the aluminum head to deal with unequal expansion rates of the metals and the copper/asbestos inner gasket has been very hard to find.
- The original exhaust sleeves to which exhaust headers attach are prone to rust-out and are hard to replace.
- I think I paid over $200 per exhaust valve when they needed to be replaced.
- You'll need to modify a wrench so that if will fit the nuts under the cylinders. It is completely necessary to “snug” those head nuts regularly.
The good news:
- The carb hangs from the oil pan and stays toasty for winter flying.
- It is cheap to feed.
- It is wonderfully smooth and mine has been completely reliable since 1987.
- If I recall it has more main bearings than the Continental too.
- And, there is almost always one sitting in the back of someones hangar. I've seen them sell on eBay for almost nothing.
- When you are done with it, a museum will be happy to take it off your hands.
Best of luck.