Some districts won't elect someone you'd recognize as conservative. Would they be better off with a Democrat, who, by your own view, would likely be more liberal than any Republican would be?
Almost all of the old Rockefeller Republicans -- the East Coast liberals -- are gone. Except for those two women from Maine, there doesn't seem to be very much of a liberal (or what the press would call a "moderate") wing of the party left in Congress.
Rather than the old liberal ("moderate") bloc, you have Senators and Governors who are a little more corporate, a little more country club than the rest of us. They may be a problem, but they're not the main reason Republicans are in such bad shape right now.
For example, every Republican in the House voted against Stimulus-Porkulus. To me that's a sign that this RINO thing is getting to be a red herring. People love to talk about it, beyond whatever real importance it has in politics today.
I didn't have time to read through your whole article. Some of it looked interesting. Two comments, though.
1) Sometimes it's not a clear-cut case of liberals/moderates vs. conservatives. Oliver North was carrying a lot of baggage that would likely make many Republicans and Independents hesitant to vote for him.
Sometimes the problem is the baggage a candidate has, not an ideological split. Whether or not you or I would have been enthusiastic about North's candidacy, it's not a good test case.
2) My guess is that very, very few Republicans voted for John Anderson in 1980. Most of Anderson's support came from liberals and Democrats who were disillusioned with Carter, or from those who were already ex-Republicans. There weren't large scale defections from Reagan to Anderson. At least, I'm not aware of any Republican elected officials who endorsed him.
Reagan was able to hold on to even very liberal GOP Senators. That's because he knew what was important and was able to prioritize. He wasn't distracted by side issues.