twin cam coversion 2000 dodge neon

I'm not a experienced Dodge tech but I'm sure that it will not work. Maybe if you swap in the entire engine... Find a Dodge forum and ask there.

yes it can be done, having a 2000 makes it a bit easier too. you'll need all the dohc timing components, timing belt, idler pulley, and timing belt covers. you'll also need the dohc intake and exhaust manifolds as well as a 1gn TB. you'll need to extend the coolant temp sensor since its on the other side of the head. The exhaust flange is different between 1gn and 2gn so you'll need to either weld on an adaptor or just use an aftermarket exhaust. Also keep in mind the CR of the engine will drop to 9.3:1 with a dohc head because of combustion chamber shape.

As tenspeed said it's easier to replace the entire engine with a twin cam one and change the exhaust and most of the ancillaries than trying to frankenstein one out of the old engine and a lot of other parts with a very limited chance of success.

Why go DOHC? Why not swap to a Magnum SOHC from a late-model R/T? There's less moving parts and they put out the same power.

gotta admit matt probably has the best advice here