[Woodz428]

Like many I use ultra high temp permatex and have never had a leak. Something that may avoid another leak, regardless of what route you take, is to re-check the header bolts periodically. The expansion and contractyion properties tend to cause the bolts to lose torque over time. I recheck mine at least oncfe a year while I check the other fasteners. I also use thread-lock on the bolts, whether that helps or not is uncertain. But after decades of running headers on many different cars, I find that the re-torqueing of the bolts is the best preventative exercise.
I have also ,over the years, found that running a file over the flange reduces irregularities that can promote leaks.
If using a permatex high temp sealant, it is best to snug the headers up and allow the sealant to cure prior to final torqueing. I believe that many times the curing process is overlooked and the headers are torqued up when installed, that doesn't allow the sealant to set and causes it to be "squished" thinner than it should be, creating the potential for leaking.