Need some help getting a bolt off...

[Hot Rod Surfer]

Actually Im trying to get this plug out of the manifold of my 350 and find that its been locked tight and wont budge with my puny efforts to get it off...

My question is, since its a brass plug, should I try an impact wrench or just get a bigger cheater bar??? Ive tried some pb blaster to get rid of that lock-tite, but...

The first picture is the offending plug, the second is the old temp sending sensor and the third is the location of this sensor (Im putting the new sensor for the new gauge up in the problem plug location)!

Thanks in advance!!!