Clarification here might help. Amp blows the fuse when turned on with 6080 in, yes? I see that you measured the resistances with a 6AS7 installed. Did you also power it up to see if the fuse blew with the 6AS7 in the socket? If the fuse holds and voltages are OK with the 6AS7 it could be the 6080 was damaged by the initial miswire.