I am wondering about how compatable the motor from the neon is with our 420a. I know that the head it turned so that the exhaust is in the back. does this mean that the valvetrain parts are not usable or do they just need to be changed around. Could a person buy a neon motor, build the bottom end and then put the head from their motor on it. Thanks for the help....

Everything except the head is the same. You can use a Neon block.

Here you go-> http://www.2gnt.com/dcforum/DCForumID30/1933.html