I've been making cider, wine and beer for 20+ years, don't have a PH meter and don't have a clue what my PH is of anything I make.
Yeah, I know I, should really get around to getting one and get with the modern program, but I just like to keep most things simple.
PH is just a number and by changing that number you are changing other things that you'll notice.
Early on, I tried making adjustments to wine grape juice without really knowing what I was doing and after a few seasons decided to just let the wine/cider be what it is and blend it to taste after fermentation. I've made "perry" without real perry pears and the results weren't all that great.
A good portion of it got used for cooking, but some I blended with cider that was too acidic as it was. I've got some perry pears in the ground now, and I'll probably start getting enough pears when I'm too old to drink anymore. So if you want to make perry, get some land and get those trees planted.
If you have access to real perry pears, then there are some perry makers around, ask them what a good blend of varieties works.
So my 2 cents: Toss in your yeast and let your pear juice ferment and then let it settle and taste it. Make adjustments later, but I would suggest making a cider with some acidic tart apples and using that for blending. If you are concerned about infection, there are other ways to deal with that including adding sugar to bump up you ABV, fortifying the beverage with spirits or using sulfites.