I just talked to the man that had the engine in my 41 reworked, he said the builder removed the sleeves and installed larger pistons. I'm not sure what pistons that would be. He also said they reworked the heads, installed a mild cam, boiled the engine and radiator, new thermostats, 94 carb, fuel pump. He said it cost $3500 for the work, he doesn't know if the lifters are adjustable or not. I would hope so, with a new cam, valves and seats. I will talk to him again and find out who did the work, they may still have a copy of the invoice. Al