Easier said than done with everything in the car. Rubber caps are supposedly only good for leaving you stranded. Drilling and tapping is an option but that would probably result in me cracking my water pump. I think I'm going to go with aluminum heads and roller rockers at tax time next year so I may be able to come up with a better solution then. I've had good luck with the Summit AN fittings/adapters so far so I think that's my best option.