The only spark plugs I know of that don't came with gaskets are the tapered seat plugs
You don't want to use them in any Hemi motors I know of currently: confused:
As far as heat range I like to run the coldest plug I can that runs clean and doesn't get black at light part throttle driving
On your deal I would try a Champion RN9YC or maybe a Champion race plug. Autolite street plug # 3923 or maybe their 3922. Autolite # 3911 or 3910 on their race plugs.
I'm not current on NGK plug #s