I'm going off code 100 track. It just doesn't look right. I've been experimenting with increasing the sleeper spacing on the code 100 track a little. I'd like to do it with the code 75 track too. All my points are code 100 but any new track i'm going to buy will be code 75 I think.
It depends what running rails you are using. I used to use Peco code 100 with their code 60 juice rail. That looks tiny compared with the Code 100 so I stopped using it. I briefly joined the Scalefour Society (they promote P4 gauge) and I had access to their conductor rail and chairs. They look great. My avatar with my A stock train on it shows Peco Code 100 with the Scalefour society conductor rails. I'm really happy with it.
To conclude, I think I am going to start using code 75 track now and space out the sleepers a little. I'll lay the neg rail flatish to the sleepers to prevent catching.
I found with the code 75 (which I have used on all of Intervale), it is best to drill about 0.5 mm down in the center of the sleeper to accept the base Peco pot for the -ve rail. This just about puts the surface of the code 60 at a scale height above the running rails and reduces bits of train hardware catching on it. Metman, it is worth the investment and just use the code 100 for hidden sidings.
Of course, with code 75, any Lima stock you have will need the wheels replacing as the 'pizza cutters' that are fitted will bobble along the chairs due to the depth of the flanges. At least it gives you an excuse to replace Lima wheels which can only be a good thing!
As for the adaptors, they seem to be a standard Peco line and so s-h-o-u-l-d be available at any Peco stockist.