correct filler neck for 70 swinger 340?

new non vented tank already bought. not turning back there. it does have some hot restarting issues that I'm sure the ECS will help....but its a weekend warrior and driver quality....so no biggie. the filler neck has the vent at the top like that one in the ebay auction I linked too....but I'm wondering if I should have that vacuum cap? it does say vacuum pressure on the under side of the cap....should it be a non-vented cap for 70 swinger 340 no California car?

the insulator I believe is the one that came with the edelbrock carb....I think....I just measured it and it was 1/4" thick. I may have used the one that came with the Daytona carb rebuild kit I bought for the original AVS carb before I bought the edelbrock. i'll have to go look in the carb bock to see if I have a thicker one.