RAID 5 - All superblocks gone due to MBR/GPT mishap - how do i figure out chunk size?

[den RDC <denrdc@gmail.com>]

Hello

Due to a nasty (human) error,  4 2tb disks in raid5 have lost their
1st megabyte of data ( including superblock ). In an attempt to get
the array to a state usable enough to at least attempt data recovery,
I have been trying to re-enable the array using various chunk size and
partition start offsets, but i cant seem to get it anywhere near a
consistent state ( recovery tools only return files or pieces of files
smaller then the chunk size, indicating alignment/chunk size
inconsistencies ).

The data I do have is :
- the order of the disks
- the pretty solid assumption that all data, even parity should be
fine for most of the disk except the very beginning.
- the exact size of the MD device before it got corrupted.

Is there any way, however adventurous, to glean the missing data (
chunk size, chunk alignment/offset ) from analysis of the existing
data ?

Kind regards
den_RDC