990 head replacement. The 088 and 990 heads are likely fairly similar. Though the 088 exh ports are pretty rough, as well as the bottom of the int ports.

990 heads can be ported better than Brodix 312s as delivered, but will take the lead once they get some attention with cartridge rolls.

2.25 Int valves should help a bit from the 049s.

I've got 2 sets of new 088 heads that need some mild cleanup. It's amazing Mercruiser managed to get them to perform.

Mike Jones from Jones Cams is one of the best cam grinders around. $550 is a custom cam charge for Hyd Roller. He has a very extensive marine engine spec sheet to dial a cam in for your needs. Worth checking out to see what he says. He's on Speed-talk.com forum as well.

Custom Camshafts | Jones Cams

Honestly, I don't know. All I've gotten out of the 272 is 63mph and that's on par with 375hp 496 and 415hp 502s in similar years. I wouldn't mind changing the heads and see the gains. When I built the 489 I had high hopes and really would have liked to get 70 out of it, didn't think that was unrealistic, but here I am surrendering to maybe going for mid 60s. The cam in that is a comp designed marine, 242/248 .566/.566 and 9.85:1 compression.

I will definitely check him out. Id rather have something built around my setup. I just bookmarked his page.

You might be hurting intake flow with the small bore and 2.30 intake valve; a 2.25 would be better. If anything, you aren't really gaining anything with the larger intake valve unless you were going to rev the heck out of it (not going to do that in the boat).

Have you played with timing on the 489? And are you sure on the actual compression stated?

I run 2.30" and bore notching takes care of that issue.

Compression is 100% accurate, measured the head cc, I measured the piston depth, and had all the other info needed. My timing is currently at 38° wot and pretty much stopped there. My block I notched for the intake valve prior to assembling with the Brodix heads.

Bore notching is effective in BBC...with the over hanging heads on the bore + large valves.
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Don't the Brodix 312s have 2.25 Intakes?

38° is def on the high end.

I was considering pulling out back to 36 and see if I gain any RPM, I just can't get past 5k rpm no matter what right now. I do run 93 to keep it on the safe side. The Brodix heads do have 2.25 intakes.

I am going to remove the single plane intake manifolds on my 482cid engines and swap them out for a a pair of dual plane air-gap intake manifolds... Those will definitely give a 482cid Marine engine a good kick in the pants. Single plane intakes are a little too sluggish for a HEAVY 40 ft boat only making peak power @5000 RPM.
If my 482's were going in a 32' boat then a single plane would work a little better depending on the combination.