Use 1" PE from the pump up, you'll never see any difference. If you think about it, you aren't running 1" or 1.25" any farther than your pressure tank tee, past that it will be reduced to 1" or 3/4". We've used 1" on 1.5 hp pumps down 500'.
I suggest you go to any pump or plumbing supply house and ask for a SS 1" insert/barbed x 1.25" MPT regular length fitting. I'd use the SS 1 x 1.25 male instead of brass but a 1.25" x 1" reducing bushing and a brass 1" x 1" works, you just have two threaded fittings instead of one to install.
PE rolled pipe comes in black or blue.
You buy it by the psi rating and in rolls from 100' to 500' and at some places 1000' rolles. In your case a 100' roll of 160 psi is great and you get any ID in any of the ratings; 75-200 psi.
1.25" is not stronger than 1" unless it is rated @ 125, 100 or 75 psi. 200 psi is overkill for only 100' deep and your size pump.