Sun has a Product Solution for regen.
http://cms.sunhydraulics.com/cmsnet/LitDownloads.aspx?lang_id=1http://cms.sunhydraulics.com/cmsnet/LitDownloads.aspx?lang_id=1
Your requirements are very stringent. I don't know if they can be met. Look closely at the turn down raio. The only meters I know of that will do a 100:1 are positive displacement.
These are 2 that we use.
http://www.maxmachinery.com/top.html
http://www.vse-flow.com/english/flow-counter.php...