new motor,low oil-pressure

I just built a 351w for my 1990 GT. The crank was cut 10 thousandths of an inch under, and i added new speed-pro pistons and eagle connescting rods. It has the stock oil pump as well as lifters and pushrods. After months of procrastination I finally put everything together and now I am getting low oil pressure and a knocking noise coming from the engine. About 10 lbs at idle. Could anyone give me some suggestions, I am completelystumped. Thanks

BY SAYING THE STOCK OIL PUMP, DO YOU MEAN YOU PUT THE ORIGINAL BACK IN IT, OR IT IS JUST NOT A HIGH VOLUME?  

it is not a high volume  

New just means nobody has owned it before you.  When I used to sell performance parts, on a few occasions I had "new" pumps come back....even from top-dollar manufacturers.

Did you check tolerances prior to, and during assembly?

I hate to be mean but that was wrong to put in the stock oil pump. Honestly, you put in a larger engine and you probably put in a single gear pump.

That was a no-no!

Up grade!!!!

Put in a high efficency pump and watch the pressure!

I have no idea what you were thinking?? Save a little money?
Well 1st: always upgrade your pump to get the pressure your car needs. Don't try to save a few bucks cause it will hit you in the butt later.

You want real advice.....

New upgraded pump (dual gear)and replace with new moroso billet shaft instead of that little skinny one, those stock shafts suck and break alot. That is what I did with all my 65-72 mustangs. Never lost pressure and it kicked put on the tracks! it was worth the hassle in the long run to do and not let it go till it got worse!

I know you are hating doing all that work again, but if you do it right the 1st time it should have been fine!

I would like to know who sold you that engine and did not tell you to upgrade your oil pump? That was a bonehead move! You don't have to but it is highly recommended!

Have fun!