The TA-230 has 6V6 tubes as the outputs; so, while 6V6s are a great sounding tube, it won't deliver 30 watts/channel. The TA-260 has 7355 tubes and the S-7000, S-7700 and S-8000 receivers use 7868 or 7591 tubes and all these should be more in line with your power requirements.
The H/K is a bigger unit vs. the relatively compact Sherwoods and so is perhaps a little easier to work on. I like the 7355 tube sound but it is not in current manufacture and old stock are not exactly plentiful. However, there is a 7591xyz (not a regular 7591) that can be used in place of the 7355 and is available relatively inexpensively. It is a larger tube than the 7355 but will fit in the TA-260. The receiver could also be modified for 6L6 tubes.
The Sherwood receivers are more compact and getting the output tubes in an out can be a bit awkward but they are definitely good sounding when restored to spec. The painted front panel of the Sherwood is sometimes an issue if you are concerned with cosmetics. Many have areas of the paint worn through, usually around the volume and source select knobs.
IMO, these are all very nice sounding and worth restoring and they do seem to be a good value in comparison to the generally more costly Fisher, Scott, Pilot etc. brands.
Good luck with your search.
