The Holley will offer more tune-ability and more top-end power.
If your marine 460 is a King Cobra 460 and has the forged flat top pistons, then your compression ratio is currently about 9:1. The King Cobra engines were not released until the mid 1980's and I suppose you would have mentioned that name if you have one.
If your Ford Marine 460 has the dished pistons and since you are considering spending a bit more, there are a few different ways to go now. Your compression ratio in the dished piston Marine 460 is a mere 7.7:1 or so. If this is the case and you are willing to spend a bit more, then you can go with, say, a CompCams CCA-34-235-4 (<---Summit Racing p/n). This cam has a slightly tigher LSA and will help increase cylinder pressure. Unfortunately, it's difficult to find a camshaft with more duration that doesn't also have more lift, and the springs in your engine will not last long with lift much greater than these two camshafts I suggested. A cam kit with a spring upgrade changes all that, yes, but at that point you should also be changing out the 30-year old 2-piece valves, which means a valve job, etc.
Installing D0VE heads on the dished piston Marine 460 will increase your compression ratio to about 9.1:1. Since your 460 already has the Marine cam which is essentially the 429 Cobra Jet cam, it would be a good match with the compression ratio increase. They accept roller rockers (your D3VE rockers won't transfer over without some mod's).
I have a freshly ported & machined set of D0VE heads ready to bolt onto an engine. They are cleaned & blasted, magged, nicely ported, smoothed chambers, 3-angle vavle job, oversize stainless 1-piece valves, big springs, 10-degree retainers and locks, resurfaced, etc. It is possible to see as much as a 100 hp increase with the head swap, and the potential to make more power (with the right combo) is awesome. Properly set up and in the right engine combo, these D0VE heads could support well over 600 hp in a 460.
Call or PM if interested,
LO