Is there a way of holding the upper besides buying the vice blocks so i can remove the barrel nut(or what ever its called) so i can replace it with a FFHG? And are the threads normal or reversed on the nut? thanks

The threads are normal right-hand, you must remove the gas tube first.  You should be able to improvise using a normal vise with heavy padding to protect the upper.  Do not squeeze the upper with the vise, just use it to prevent the upper from spinning.  During re-assembly do not overtighten.  You can use low-strength loc-tite, get it snugged, then turn to next gas tube alignment hole, that is tight enough.  Mil-spec is 35 ft.lbs. if you are inclined to torque it that far.

Thats great news, thank you.

Unless that barrel nut is v-e-r-y loose, you will f*&^% that upper by taking shortcuts.

Having said that...

Do not use Loc-Tite. Stick with moly-disulfide grease. Torque barrel nut to 31 ft/lbs. minimum, not to exceed 80 ft/lbs. to align the next slot in the barrel nut.

There is no need to ever use LocTite anywhere on an AR 15 assembled with stock, Mil-Spec parts.  If you assemble things correctly all will remain tight.  The crap only results in damaged parts the next time you need to disassemble it.  By design there is only one fastener that uses a self-locking material applied to the threads.  That's the buttstock screw.