318 garage clear rebuild

I just got an offer to mill the block for 140€ plus tax in Germany

so if the block would be zero deck, and with some flattop pistons i would be just over 9 to 1 compression with 73cc heads and 0.040 head gasket.

So if I could find flattop pistons with about the same weight could i just exchange the stock ones with them?

As said i dont really need this motor because currently the 408 is in my car, so its would be really a budget build for fun as a backup