1st question;
I have a1969 AMC Javelin and would like swap the engine for a.

375hp 345ci Crate Hemi or a

485hp 392 Crate Hemi

2nd question;
the engine that is in the Javelin is the 290.from what I have read the the 290 block was used as the main block for most engine builds. I bored the cylinders 30 over and replaced the 290 head and swapped them out for the 390 heads. Is there anything I should keep an eye out for. The car is not running at this time. The last time I worked on it was 28 years ago. Before I left for the Army. I rebuilt the eng, now I will have to rebuild it again.

 

Valve pocket... The difference between those heads are. They just have a slightly larger exhaust valve... Heads are close to the same other than that....