will a 500hp intake work on a older 454 motor

Yes

Yes as long at the older 454 has rect port heads. If oval port than no.

BT

You can put a rec port intake on a oval port head, you just won't see much of an improvement out of it.

The HP500 intake is a rec port, single plane, high HP intake. If you're going to put that intake on a 454 it should be a high rpm, high Hp application.