If the file is for GMS1, then the best way to access it will be in GMS1. If you need the contents in GMS2, then the best bet is to see if whoever created the GMS1 version can supply them. If it is an abandoned asset that is no longer getting updates, then you may be able to find someone who still has GMS1 installed(going by the forum posts there are plenty of people still). This isn't a good idea if it's a paid asset though.