Compression good 150 ~160 psi, Spark good ,Timing good and New plug. Valve timing is right, Valve clearances are good. Exhaust clear. Have tried all things on fuel side choke no choke add fuel to filter fuel in plug hole etc.What have I missed.

 

Welcome to the forum! Have you cleaned the carb,replaced worn parts? Have you looked real close at the exhaust lobe when you checked/adjusted the valves?? You can have a cam lobe partially ground down,but will still push the exhaust valves down but not far enough to be able to crank. Have had em idle good,but wouldn't take throttle, would pop back through the carb,or not run at all.The Magnum 425 fell right in years 96-99 when a lot of cam failures happened on them and the 500 engine. OPT

 

Yes cam has been replaced (took awhile to figure that out!) I've done some work on the carb but will recheck thanks>