Probably could but I'd say no. The first thing you should do if they're local is to manually spin the flywheels by hand. If they won't move then I would steer clear. The lst should have plenty of parts around since its a very popular rig and if I'm not mistaken, some of the xxl parts should fit as well.
The Aftershock is still a decent kit. The only differnces between the LST2 and the XXL is the XXL chassis is slightly longer which also means longer drive shafts. The XXL comes with Plastic shocks instead of Aluminum but the shocks are still decent. The XXL comes with the updated radio and the telemetry stuff. The XXL comes with a .28 engine, the LST2 came with a .26. The XXL comes with different wheels but the same tires. Some people like the new wheels because they have a center cap incase your wheel nut comes off you wont loose it. other people dislike it cause it 6 extra screws per wheel to deal with when working on the kit. Oh and the LST2 came with better servos IMO. JR servos vs. the Losi ones it comes with now.