I also agree that a 70ish 4-stroke is what you want. Pick the brand you like (or price)

And I don't know WHY people say they are any more difficult to tune than a 2-stroke. If anything I find them easier to tune - and I don't need a tach to do it either.

The only two things you need to remember with a 4-stroke is

1 Use an OS "F" glow plug - they are more expensive that a 2-stroke plug, but a 4-stroke won't run properly without one

2 Use 15% fuel - I like Cool Power, but I have used others as well with good results