Header Doesn't fit??..... Anyone had this problem

[Siege]

Hey guys...

I just spent 6 hours putting on Xaio Garys Cat-Delete Exhaust header (Painted it Orange )

But.... The bolts to the block did not work... Did anyone else have this problem. The header is not thick enough off of the block, because the bolts on my block are not threaded all the way down.

I have it setting in there with large nuts as spacers, but it sounds awful because I can not make a tight seal...

Any suggestions?!?
I will attach a picture later

Thanks,
Lance