Don't bother wasting your money buying D0VE heads, IF it has them fine use them if not then use what you have (exception is if you have D2VE heads, then replace them with anything else) D0VE heads don't flow any better then D3VE heads and are identical to C8VE and C9VE heads (yet everyone says go out and buy D0VE and waste the money) there is nothing magical about them they are just passenger car heads. The only advantage with the early heads is compression, bolting them on a motor you aren't doing anything else to will gain you power due exclusively to the rise in compression but since your looking at rebuilding the engine just choose pistons that will get you the comp ratio you desire with whatever heads are on teh engine now (unless you decide to go aftermarket heads)
IF you want to dump money for a lot of HP then go with a stroker (and then definitely don't go with D0VE heads, even with huge dish pistons you end up out of pump gas range)
Making a 400hp 450ft/lb 460 is a breeze in comparison to the 400, and most of the guys that claim that with a 400 have never had it on a dyno, but it can be done. But with the same basic build the 460 will be 460hp easily. Remember even in 71 when the 400 was had higher compression and was net rated it made a whole 260hp VS the 460 for the same year at 365 from the factory. Pretty easy to see which is going to be easier to get to 400hp.

 

Thanks fella's. I'm keeping the 460