[metalmulisha3x]

I was wondering if someone could give me a good estimate of horsepower, 350 four bolt main, bored to 355, 280H magnum cam 480 lift, vortec heads 64cc, keith black flat top pistons around 10 to 1 compression,.

 

[Ghetto Jet]

I bet it makes about 380 at the crank.

 

[78 monte]

I'd say with the right carb/intake and exhuast your could be makeing a little over 400HP.
One thing Vortec heads max out at about .470-.480 lift check your retianer to seal clearance befor you fire it.