I'd go with the 14 inch crosman and save you the hassle of of using the diana chaser I'd leave the chaser as is .Have a Diana Chaser barrel ( Rifle length), can I attach to my Crossman 2240 ( plastic breech).
watched several videos, the Diana would have to be shortened a bit and a screw hole drilled on the bottom. The upper screw on the barrel band is the easier part.
Any advice? Or just easier to buy a 14” barrel made for 2240?
I personally do not like the plastic breech of the 2240 there is very little space in the front of the breech to insert the barrel
I usually replace that breech with a steel one. the plastic has no way of attaching scope whereas the steel does.
I find that the steel breech is sturdier. but it's up to you.