4.39 ROM for RPCEMU from CD

Hi everyone.

I have two CDs (6.20 Select and 4.39).

If I want to make a ROM from 6.20 Select CD I write the following command in Unix:

tail -c +21 Select6i1 > Select.Z
uncompress Select.Z

And the question is:
What should be number of bytes for the Unix tail command for OS439 file in 4.39 CD?

Thanks in advance.

I believe the RO6 rom is 4,194,304 bytes and that the RO4.3x rom is a similar size.