Pistons and rings

[Jelonek]

Hello guys,
actually I tried to rebuild old engine from 1966 Toronado 425 super rocket. This is a really great enjoy I get all parts from specialist in USA and it seems to be everything okay but I have a one question and perhaps has somebody here any idea?
We built almost everything, but when we put only three pistons with new prepared rings inside, then I can’t move the crankshaft with my hand
The pistons have an oversize of 0.02 and the rings were specially bought for them and are of course ground accordingly. Everything is adjusted like in the textbook and should work. But I still have the feeling that it is a bit too tight. Is it normal that you can no longer turn the engine by hand after just three pistons with new adjusted rings? Unfortunately I don't have enough experience with this. It works with an extension. We haven't installed all eight yet, so I can't say how it feels when everything is in. But with three and even four, turning is very difficult and tight. We've checked all the dimensions again and again and they are correct. Do any of you have any ideas or is this normal? Has anyone of you done this and had the same feeling and yet everything still works? I'm attaching a picture of the pistons and a picture of the rings so you can get an even better idea.