So I am finishing up my motor for my 99 burb and need to get taller valve covers and really like the look of the fabricated aluminum covers. I want a leakproof filler neck and dont want to go with a push in. I would like to get a billet neck and cap and have it welded on but all I can find in NON-vented caps. I have heard of this causing issues with seals so here are my questions.

Will it make a differance? Do I just add a breather to the covers?

Thanks for the help,
Nathan