LA engine Magnum Heads Pushrods?

I believe 7.65 is what is recommended but there are a few variables that can alter that.

They are

Rocker arm type
Lifters (solids flat tappets take longer pushrods than hydraulics)
If and how much the block and/or heads have been milled

IMO you should always measure with an adjustable pushrod to verify exactly what YOUR engine needs. My LA with magnum heads, Harland sharp rockers, solid FT lifters and the block square decked to 9.59" ht. took 7.55" pushrods

Also keep in mind you heed to use lifters and pushrods that "oil through"