Do I need a hardened intermediate shaft for a HV oil pump?

Couple things here, there is a difference in an HV and HP pump. "Most" high volume pumps do NOT come with the high pressure spring installed, so out of the box, a melling ***-HV is high volume, standard pressure. Sure they make more pressure than a $15 napa OEM replacement, but thats not their intention unless you swap the springs.

next, the hardened shaft is a requirement with an HV pump as pointed out above..but i have never had to ream a shaft bushing. you should have enough clearence.

lastly, as daliant pointed out above, the HV pump is really for performance engines. If you put this in an engine with a STOCK 5qt capacity pan, you're going to suck the pan dry at high RPM. you'll need an aftermarket pan with 6-8 quarts to be safe. unless you never go above 4500RPM. you might want to invest in a $40 OEM style pump, before you spend 2-300 on a oil pan.