Plugs to cover water and oil ports after EGT swap
 

What have you guys used to plug the extra port on the back of the head at the water outlet and where the dipstick tube is for the escort GT BP engine? I'm going to be tracking my car and bought some little thin rubber plugs at autozone that just clamp on and I'm not feeling very confident in their longevity. I did a couple track days with it NA and it was fine, but I'm wondering if there's a better solution that I can do to it while I'm tearing into it it this winter. It's basically just 2 open tubes that need capped off around 3/8" diameter. I suppose I could put a bolt in a fuel line hose then put a couple clamps on but there's got to be something better out there.