Heli Coil-Time Sert Advice

[bad68]

OK. I Didn't take my time and rushed installing a helicoil in a stripped head bolt hole in my BB. The stud is crooked and I can't get the head on. I have a time sert on the way. It's actually the big sert and it will allow me to use my 7/16-14 stud. Any advice on drilling and tapping so I don't mess this up this time?? An old gasket maybe or some kind of template so I am straight??

Anyone done this with the motor in the car?? If so what did you use as a guide?

Thanks.