Pack a lunch...
As to your kits, not saying they are made up of inferior stuff. Just do your homework, is all. Builders and racers have preferred vendors for a reason, and it's usually not price. Generally, you get what you pay for. Like I mentioned, I won't use anything other than Fel Pro PermaBlue head and intake gaskets. Personal preference and good experience with them. Others here may have equally valid options and reasons for their choices.
EDIT: Generally, with places like Mancini, a phone call will get you all the info you need. Good vendors are generally eager to help. You should also ask the important questions like: "Are these NOS, and if so, date of mfg?"
A buddy of mine recently bought a NOS gasket set for his motorcycle, unopened, that literally crumbled in his hands when he opened the box. They were 22 years old.
