SO I NEED TO REPLACE THE OIL PUMP IN A 2.6 WTF IS THE DEAL?

[80D50SPORT]

SO I WANT TO REPLACE THE OIL PUMP THE NEW USED ENGINE I GOT FOR MY 88 RAIDER AND THE ONE A GOT FROM CARQUEST HAS A CAST IRON CASE AND THE ONE COMING OFF IS ALUMINUM .. IS THERE SOMETHING I DONT KNOW HERE? I KNOW SOME PEOPLE SWEAR BY MITSU ONLY PUMPS BUT THIS IS A BUDGET ORIENTED BUILD AND IF THE MOTOR NUKES AFTER A WHILE I'LL PUT A CARB'D 2L HEAD ON A 2.4 AND PIMP BUT FOR RIGHT NOW I GOT THE 2.6 AND IT'S A GOOD RUNNER I JUST PLANNED ON PITCHING THE BALANCE SHAFTS AND PUTTING A PUMP IN IT BEFORE I STICK IT IN THE RAIDER..