Chris-PA
Where the Wild Things Are
That cylinder will not fit a Poulan 2050, it is a later "strato" engine. The part number for a PP260 cylinder is 530069720.On the right side of the pic I attached, there are two things I believe are called circlips? I'm not sure, but if I have a 36cc poulan I'm upgrading to 42cc do I need to have these replaced as well? What are they for?
Strato 2 stroke cylinders use different porting to delay the arrival of fuel into the cylinder, which reduces the loss of unburned fuel out the open exhaust port. That can't be done with simple "open" transfer runners, so those pieces were a rather clever way to close off the transfer runners without a more expensive "closed" casting. None of that is relevant for your engine though.