Have you ever tried that nifty search function on this board? It truly works wonders! But, until you learn how to use it, I will tell you what you want to know.
What you are looking for is a set of Belltech 6400 Shackles. They are made for (I forget the exact years, but) Mid-80's to mid-90's Chevy 1500's. They have them at summit for about $26 a pair, the ones I bought weren't belltechs, I think they were summit brand, but they are the same thing. All the rear springs on Rangers are 2.5" wide, coincidentally so are the springs on those Chevy's. So, if you have a lowered silverado sitting around for parts, measure the spring widths, and if they are 2.5" wide, those shackles would work for you!
And for your second question, any amount of lift is safe, as long as it's setup right. As far as those shackles, they will safely net you 1-3".
