The problem with a folding rollfilm camera of this type is that the front standard will lock into a position designed for the focal length of the original lens and it is unlikely that you can do much to change it. I recently fitted a 55 mm lens to a folding camera of this type and pretty much had to scrap the whole door / bed / folding mechanism.
If the Holga lens has a focal length of 85 mm and the original lens is 75 mm them you might be in trouble. You need to be 85 mm from the film to get infinity and further than that to focus closer. You might be lucky, too... the focal length of the original lens will be taken from some 'nodal point' - which would be somewhere in the centre of the combined lenses. Sticking the Holga lens on the front might be far enough ahead of that point to gain the extra 10 mm you need. Or you could add a rubber washer or something.... You need a bit of ground glass (or frosted plastic, or tracing paper) inside the camera to check the focus. For landscapes, you really need the lens to focus on a hypfocal distance for the aperture you use most, say 30 feet for f16. I bet the Holga, being used for 'people snapshots', is focussed closer than that... Might be quite tricky to focus a soft lens accurately, but get as close as you can. No idea what the speed of a Holga lens is - but it will be the same speed whatever camera you fit it too (unless it loses it's stops when you remove it).
Actually, the position of the stops with a meniscus lens are part of it's rudimentary correction, I think. Placing a different iris a different distance from the lens may change the 'look' a bit - possibly not in a good way.
But I like artonpaper's suggestion best. Every camera has it's own characteristics - if you have a working Solida, why not use it as a Solida?