273 to 318 swap 65 dart vert

Ok so here's what I do know. It's a pretty common performance mod on 273/318 LA engines to use 360 heads but mill them .50 to bring the compression up. I know I need to pull the engine apart to determine if this has been done. the person I bought this from got it from his uncle who is now deceased. Eventually that's what I'll do. I most likely will look for a 360 and rebuild it to drop in and then go through the 273 on a discovery mission. But 1st I'm gong to build some fender-well headers for this car. I am hoping that will help. This engine is just a temp for this car. I really appreciate everyone's help with this. Thanks a ton!!!