I did not refer to either Nixon or Eisenhower as conservative Presidents. Their instincts were conservative, but they governed as moderates. No small part of their accomplishment though was to make it possible for conservatism to rise and come to power in the form of Ronald Reagan. Notably, personality and circumstances matter. It is quite possible that with GOP Congressional majorities — a luxury neither Eisenhower nor Nixon enjoyed — a Trump presidency may follow GOP conservatives in Congress on many issues. Trump’s alliance with Sen Jeff Sessions as to immigration is to me a key indication that such a dynamic will prevail if Trump wins.
I saw little to nothing that would qualify either as "instinctively Conservative." Rhetoric, perhaps, but they governed both as liberal Republicans. They were content to manage Socialist government of their Democrat predecessors and expand upon them. The antithesis of Conservative instincts. Nixon himself may have been anti-Communist, but he promoted an agenda that moved us well to the left.
"No small part of their accomplishment though was to make it possible for conservatism to rise and come to power in the form of Ronald Reagan."
Reagan was a reaction to Democrats and inept governance by their liberal Republican counterparts. Ike and Nixon did not want a Reagan or an actual in-practice Conservative President (although Nixon played the good soldier for Goldwater, he knew he was not going to be elected. Absent JFK's death and his not seeking a rematch, Nixon likely would've ended up behind left-wingers Rockefeller or Scranton). There's a reason these guys were called "Establishment Republicans."
"It is quite possible that with GOP Congressional majorities — a luxury neither Eisenhower nor Nixon enjoyed — a Trump presidency may follow GOP conservatives in Congress on many issues."
But Eisenhower did have a majority in his first two years, which he let slip away. By 1958, the Democrats had a 2/3rds majority in Congress. An epic-level fiasco under his leadership that left the GOP unable to be competitive for majority status for 4 decades at the House level. If Ike had been a Democrat, he could not have inflicted that level of damage to the GOP. As for Trump "following" GOP Conservatives today, I wouldn't yield to a group that hasn't shown any sort of leadership under Zero in stopping his agenda. He's going to have to take the lead and decisively so.