closing holes just in selectet areas

[frank.stremke]

hello
iam trying to combine two chunks to one model and in the areas they overlap the geometry is not realy identicalk since the resolution is diferent and i have the upturning waves as a relict of arbitrary reconstruction so if i cut and delete al the parts i dont like usualy there is a smal gap which i vafour instead of a bad overlap which wil just make me trouble in the rendering (flickering textures and such)
but i dont know of any way to close the holes nicely. i can use the close holes tool but in nearly every setting it will make higly unwantet triangles trying to close things which need to be open....
ususaly what i do is close holes then leave the changes selectet (which is a nice freature) then unselect the areas i whant to keep and delete the rest
however this does not work here becuase the triangles of the closing blocking themselfes so i cannot go to the ones i what to keep to unselect them ... also my alternate plan does not work by closing the holes and then deleting big triangles by gradual selecting them acording to ther size because i would lose to many good ones to get rid of the bad ones.
so what iam looking fore is a way to close this by just closing the holes in a selectet area or a other way to fix my model maybe in blender or so
best regards
frank