An example that used to be specified a lot on Jap motorbikes was "ThreeBond" semi drying viscoelastic high performing RTV. Never mind how good it is, I've seen plenty evidence of people putting waaay too much on and lumps of it in sumbs etc... I wouldn't rubbish or discount gaskets completely either - corn flake packet material yes, but you can get some quality gasket materials specified dependant on need. And it can be quite therapeutic work with scalpels and hollow punches if you're that way inclined