Sleeve nuts are still available from Mopar , studs can be bought any parts store , Napa , O Riellys , Auto Zone Etc .
Do Not use a gasket between the head & manifold , it will fail every time !!
Use a gasket at the flange FEl Pro has them for $2-3 each , I coat them with Ultra Copper silicone & all you need is 7/16 bolts & nuts .
TTi has mandrel bent pipe not crush bent & they will fit perfectly , I think a pair is $160 or so