valvetrain upgrades

[SavageChild]

While planning my cam, I realized I would need to install double valve springs. To do this, I've gotta cut the valve seats, and y'all know the rest. However, I can't find an exact figure on the valve stem size to get new retainers, locks, or even the arbor for the cutter. I know it's gonna be in the neighborhood of 5/16 to 3/8 of an inch, but that's it. Any help would be appreciated here! Heads are stock details but a fresh casting so not really aftermarket so much as stock

 

[Merc225hp]

Don't need double springs no machine work what so ever. How much lift in this cam?

 

[SavageChild]

.377/.380 at the lobes. I'm already planning for dished pistons if I'll need them. I'll share a link to the cam page if you like

 

[Merc225hp]

Yes post the link please.

 

[SavageChild]

http://www.hughesengines.com/Index/products.php?browse=category&level0=Qi0gU21hbGwgQmxvY2sgRG9kZ2UgTWFnbnVt&level1=Q2Ftc2hhZnQ=&searchmode=partnumber&page=2&partid=30785