pushrods for mag heads on LA

What Frosty said buy or make a checking pushrod & measure the length you need to get the preload you want. i used the MP ones (7477 ?) for the conversion (reportedly NS1) & they are too long (I have too much preload) but I am going to go with them at the moment but this is a high RPM circle track eng so pending further advice i may have to change them