What are the determining factors to whether you use a 30-50 or 40-60 pressure switch?

I am going to install my pump this weekend (if it doesn't rain). I purchased a Sta-Rite H series 1/2 HP, 230 V, 10 GPM pump which will be installed in my 35' deep brick well. I am using a 1" line attached to a pitless adapter(you need to see the mechanism I welded together to mount the pitless adapter 4' down in the well. Even I am impressed with it!!) I will then trench the line the necessary 200' to get it to my building. Once inside the building I will attach a Commercial water filter, pressure tank etc.

Thanks for all the help on this site. I'll let you know how smoothly it goes.