The problem I see is that Powell could well become leader. Prior, Maudling and Whitelaw are probably all 'more of the same' and the Conservatives may end up with him.
What is likely to be different from WIGBHP would be the way the Labour Party loses. Just have to hope that Heath et al, STAY within the Conservatives as a moderating influence, the Conservatives win in 1974, but don't do anything quite as mad as they did in Gordon Banks (War with Ireland!) and the security services also don't try and maintain any terror alert.
That being done (and it is likely they would stay more 'sane') then the Conservatives bumble on for a couple of terms, tackling the Unions somewhat, being quite freemarket and making for a radically different 1980's, possibly with a long period of Labour from 1982 to the early 1990's.
Would Britain be in the EU (or EEC then)? Perhaps not.....