With the new PF's coming out, nice plastics and cab, a clean backglass, and in conjunction with all these mods, HH could easily be one of the coolest looking games out there. The art and PF design is awesome in it's own right, but the title tends to suffer from the wear and tear that occurs with the game's design and being susceptible to damage for decades prior to the HUO culture.
I've been thinking about renovating the metal upper PF ramp with some dollhouse staircase accessories to give it a 3D look.
You'd buy the stairs plain, but staining them dark wood (like a victorian home) wouldn't be too much work. Another option is to paint them a dark blue to match the stairs depicted in the attic's artwork.
I was thinking about affixing the rail posts on the outside of the ramp side walls, between each metal hole, so you look through each post. It might look best to cut them to size as you go up, since the sides of the ramp do get shorter as it goes towards the attic. http://a.co/4EW6z5d or http://a.co/1PrH4zE
They sell this top rail that's already notched and may slide right on top of the side walls, and gluing to the cut-to-sized rails. http://a.co/coeOfrP
And finally, the front posts, I feel you may only need the front two for effect, since the art in the attic shows the top of the stairs. You could get away with slicing a little vertical notch in the posts, and affix them to the front of the ramp walls behind the star post and rubber. http://a.co/cBt0wuZ
At a glance, this does appear to be doable and avoids touching the ball, and I very rarely, if ever, get airballs in my game, or anywhere near the stairs.