Big Block intake swapping..

Do not use a gasket on "both sides of the tray", only to be used on the side that would contact the Aluminum intake when an Aluminum intake is going to be used! And yes, check for fit, It is deceiving as to the alignment of the bolt in the bolt holes until things are tightened. The raised ribs of the tray will have a tendency to hold the manifold up too high until things get torqued down. Start at the front on one side and start at the back on the other side and slowly work forward/ rearward till it snugs down. If this is imposable, due to shaved this and shaved that, Stop, and re-evaluate the need for the Aluminum intake needing to be shaved also.