Actaully not a bad idea especially if he's not running way up on compression ratio say 10.5 or more because the heat transfer rate of aluminum eases the requirement on a super tight squish/quench some to where the addititonal .010 inch thickness of the gasket will not upset that requirement. This gets him around the the need to drill holes in a 350 gasket as well.Not trying to bump heads with anyone the Felpro qasket 1010 is Designed for the 400sbc it has a pre flattened stainless steel flame ring around cylinder bore as you can see in the picture it DOES HAVE SREAM HOLES' .041 thickness
Also can use 1004 same gasket with wire amd with Steam Holes difference is compressed thickness the 1004 is .039 also pictured Go to JEGS or Summitt web sight they give Pictures discripion and intended use
or just type in 400 chevy felpro gasket ,they will be a complete list of gaskets
click on pictures below
I am sure you already know but thes print o seal gaskets are Stamped ,This side up .
I like blue Locktite on rocker studs that have a bolt head on then that allow them to be torqued. The blue Locktite seals up the passage preventing a vacuum leak into the port and helps retain the stud at the torqued value without creating such a firm joint that there is a risk of pulling the threads out when removing the stud as sometimes happens with red Locktite in aluminum. Use a lubricant under the stud's flange. If you're using flangless studs then use red Locktite on the threads for the extra holding strength.P.s. which is the best way to seal the rocker arm studs???