John, I am in the middle of a complete rebuild on an F head 161 for a good friend. If you have any questions please give me a shout. While I do not have all the answers I am learning daily on this really cool engine. I have had no trouble sourcing pistons, rings, valves and guides as well as all the bearings for the bottom end and gaskets. That being said I did not say they were cheap. Looks like I will have about $1200 in internal parts alone and another $1200 in machine work. Luckily the block and head had no cracks when magnafluxed. This one is setting in a 50 Jeepster although I do not think it is original to this car it is period close and really neat. Can't wait to fire it up hopefully before Christmas.