I just bought into a partnership of a 1976 177B (FG). So far, I love it for all the reasons noted above. For my money, it was hard to beat the price to performance ratio. I hired the guy from Cardinal Flyers to come down from Chicago to Indy check it out first. He's not an A & P, but he really knows the Cardinals, and what trouble spots to look for. The only thing I felt like I really took a risk on was the engine, but the engine was technically run out based on calendar date (although not total hours), and so I assumed that it would need a major overhaul in my analysis. Given the price of my interest, I felt like it was worth it even under that assumption, and any time I can get out of the engine is "found money." So far, the engine runs great, with plenty of power.
The plane I bough into had not been flow much in years prior to my purchase. That is a red flag for engine corrosion. I am no expert, but I am told that that presents a higher risk that the cam lobes and lifters can become worn, thereby reducing the valve movement, and reducing power. You see symptoms of this wear not so much in reduction of top speed, but in fuel efficiency and climb rate. I understand that there can also be corrosion in the cylinders. I will let others more knowledgeable than me elaborate.