They aren't bad heads. They do have larger chambers though, which with dished pistons, can make a monster of a turbo or blower motor. I know of a guy that made over 700 HP at the wheels with a stock short block 460 (cast pistons and all) and D3VE heads.
Comparing heads: The D3's aren't too bad, other than the larger (~92cc)chambers. The C8VE, C9VE, D0VE are regular ol' 429-460 heads, but they have screw in studs and smaller ~76cc chambers. With flat tops, you can easily get 11:1 compression maybe more depending on bore/stroke and a few other factors. These early heads are very capable of 500 HP with a gasket match and a little cleaning in the exhaust ports. The D3's are too, but they need to be machined to accept the screw-in studs & guideplates. The early ones do not, just bolt in new studs on top of the guideplates. They're ready to go.
Then there's the D0OE CJ heads which have larger intake & exhaust ports and small chambers (~72cc, IIRC). They are in a class of their own as they are very capable of 500+ HP with no other work.
The "best" all around street/strip budget head is the interceptor head, which I belive carries a D2OE number, IIRC (correct me if I'm wrong). Mid-size chambers are good with flat tops but the intake & exhaust ports are similar to the CJ's...a little smaller, but they work pretty good.
There was also a year that had some open-chamber "POS" heads...I think they were D2VE's IIRC. I remember having a set of those, HUGE chambers, lots of little curves & bumps in the exhaust port and the intake valve guide was in the way of everything. Not much good for anything but an anchor for a very large boat.
I remember seeing a thread a while back on a fellow that ported a set of D3's and made a LOT of power with them. he felt that the exhaust port wasn't too bad (relatively speaking) and only needed a little cleaning, as did the intake ports.
In all actuality, the only "bad" 460 heads were the D2VE's and the E7TE's which were used on EFI 460's. They had tiny ports and are simply a choke for anything requiring power above 3500 RPM.
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