Unfortunately, a D5 head is a 351M-400 piece.
It is not as good as a early 351C 2V head because of its exhaust port/valve bowl.
It is the same basic casting, but they changed the exhaust port (for the worse) to keep it in line with the emissions requrements. A D0, D1, or D2 Cleveland 2V head has a slightly larger exhaust port with a better passage than a 1973 or later head.
You'd be better off to get an earlier set of heads, or a set of the Aussie 2V heads with the closed chambers.
Im not saying that you cant do up your heads that you have, because you can still port them and get good performance from them, but you'll be doing more work on the exhaust side than you'd normally have to.