Trunk latch key turns but won't budge

Hey guys! Working on a Chevrolet corvair 1965 that has been sitting in my grandpas storage unit for about 20 years. He has 2 of them for parts and stuff so we've been slowly merging the two but he thinks there are parts in the trunk of the one that won't open! The key turns but the latch has fallen through or something we have no idea. Is there any other way into the trunk that you know of? Trying to avoid brute force but will do whatever is necessary. Thanks for your time and help!