You need at least a 4" casing in the well. Most deep well jet pumps are installed in wells that don't have a 4" casing. If they had a 4" casing, they would have installed a submersible.
If you don't have a 4" casing, then you should probably live with the jet pump until you are ready to put in a new well.
There is a long thread on this forum of what one guy went through to pull a deep well jet pump. Someone (not me) can probably point you to it, or you can search for it.
You will need to use polyethylene pipe unless you want special features in the addition that include a hole in the floor and a hole in the roof to install rigid steel or PVC pipe.
A 1 HP submersible is probably a 20 GPM pump, which is a big jump from a 5 GPM (spigot test) deep well jet pump. No matter how big the pump is, it can't deliver more than the well can produce.
It is going to be a nasty job to pull the pipes (probably steel) from the deep well jet pump. You will need to rig a hoist under the crawl space, and you will want someone with an acetylene eraser (cutting torch) to make short pieces out of long ones. Don't burn the house down.