Oil pressure problems in 383 stroker motor?

i have a 350 bored out 60, vortec heads, vortec intake, when i first start my car up it has 50-60 lbs of oil pressure and then as i drive it the pressure falls off to 25-35, when i come to a stop and am sitting still it goes to 0, it makes a knocking/tapping sound at around 2RPMS but stops a little above that and doesn't do it in the lower RPMS under that, when it makes the sound the pressure is in the 25-30 lbs range, i just found out that my intake is cracked from being tightened too tight and antifreeze is coming thru the bolt holes, i just wanted to know if replacing my intake and possibly oil pump would fix this problem, thanks!