Charlie, a good replacement mic will help those radios. Don't get me wrong, they really are good radios. Its was just the poor mic and the absence of the AM mode that decided things for me.
2stock, that Kenwood is a big beast! A great radio though. Look for a flickering digital display in those things. It was a common developement in them. The TS-830 is a very similar radio but has the extra bands the FCC authorized in the early 80s. You may look for one of those instead.
The problem with the old tube rigs is the cost of replacement tubes, and the constant tuning of the output tubes. You select a frequency to transmit on, tune the radio up and you can start talking. If you move very far away from that frequency, you have to retune. If you change bands, you retune again. Being a lazy butt, I just got tired of doing that all the time especially considering the modern transister radios need no tuning.
Its all up to you though. A used TS-820 or 830 will cost $300-$400. A used transister rig will cost only $50-$100 more.
I used to have a set of Drake twins, a Swan 500, a Kenwood TS-820, A Yaesu FT-101EX, and I now have a Swan 400. All tube radios! I've had enough of the tuning!