metal intake gaskets

I expect everyone who responds will agree that you used the correct type gasket the first time. We dont know exactly where you didn't add enough RTV. General consensus is felpro gaskets, don't use those cork end pieces and remove the dowel pins from the block, aftermarket/aluminum intake or not.
I can't predict using those metal shim stock gaskets would lead to yet another do over. I leave that to those who have been down that road. I used the above advised plan to place a later model cast iron dual plane 2 barrel intake on my 273 about 3 years ago with excellent results.