Shocks for sprung over M416?

[kai38]

I did a spring over on my M416 awhile back & never put shocks back on.
How do I measure for new shocks? Measure with the trailer sitting in the garage or with the suspension flexed? Should I use the original shock mounts or have a new upper post welded to the frame?
Thanks,

 

[OldSven]

I'm in the same situation with mine. Normally flex out the suspension to get your max length and the same for compressed. Take the two lengths and find a shock that fits between those. You want the suspension to max out and compress before the shock does otherwise you will ruin the shock. I have the same shock mounts lying around and they look fine