I agree,...also, I don't know if it has been mentioned yet, but a Merc 454cid 330hp engine come stock with oval port heads---the earlier heads usually had the "049" castings and the later Merc 330's had the "peanut port" designed heads, therefore, if you try sticking a bigger cam in the Merc 330, then it will most likely fall on its face and become a dud---plus other issues like valve guide height clearances with the spring retainers, etc, You might..be able to at least get away with a very slight upgrade with perhaps a roller cam, but not much---you need to really do your homework. If you are looking for more power, then I would suggest doing some bowl-port/short-side radius work on the heads, and upgrade to a hydraulic roller if it can be done on a Merc 330, but any cam upgrade will be super limited. Check with a reliable marine engine builder that is familiar with Merc BBC stuff....especially the old 330.

In addition to what I have already stated above (I forgot to mention)....Just keep in mind that the Merc 330 usually came with an all cast rotating assembly and only a 2-bolt main block and now somebody has added turbos---yeah?---I really would not do too much more than what you already have there...just my .02 Mark