greatnightmare

So im about to tare my motor apart and rebuild it. One of the things that I am fixing is I had a helicoil in one of my head bolt holes strip out about a year ago and I needed the car back up and running the same day so I used a helicoil, but I could not find a tap long enough so I threaded the coil in as far as I could and got it to torque down to 25lbs and left it that way. Now when I get it off I will first check and see how much is left past the first repair and if its enough then I will have a shop put in a time sert (they already have the kit). If not, then I want to drill it out and tap it to the next bolt size up. I already have the right arp studs for the rest of the holes but I will just have to buy one with a large enough diameter. That being said I wonder if the hole through the head needs to be opened up anymore and also I will have to ream the gasket to fit a larger bolt. Is that a problem doing so or is there already enough room to fit the next size up bolt? I know I can always resort to the big sert kit for a 2nd time repair but I'd rather not pay 500 to fix one hole. Thanks for the help. Also please don't respond if you just think it wont work, I hope someone out there knows first hand from experience.