Installed a one piece extended 20moa weaver base on mine with short quad lock rings and my nikon 40mm scope will hit front of base if slid back to far. I've heard of trimming off the extended part for scope clearance. Maybe you could pickup a set of both med and high from somewhere you could return one that doesnt work? should be able to eye ball without installing. Cant help you much on stock decisions, hadn't decided myself yet. One thing to keep in mind that if you have a plastic stock you may need additional parts for dbm. A element chassis may not be much more fiquiring cost of dbm and if you want acis style mags.