I don't remember what the ID is of the factory spring, but you should be able to use the E3650 spring and I think it's the small Apex seal. The spring may need some spacing to get full power, not sure.
Or you could probably just order up a Quest spring and seal from Crosman.
JM's Tarantula spring will also work, but it will probably need a bigger guide made to fit it.
"You've come far, pilgrim."------"Feels like far."
"Were it worth the trouble?"----"Ah, what trouble?"