^^^That^^^
Some OE high performance blocks/engines had them.

The 454 mags we’ve built had them (88-90) but my 502s did not.

The smaller bore blocks have more shrouding. 4..47” (502) and up don’t have significant shrouding.

Exactly.

Interesting… the gaskets still have the notch though not as pronounced (I just went and looked).

i've bore notched 502's,not sure if it helped,,but it was quick and easy upgrade.

Put about 100 miles on her today down the York River. I parked my truck and trailer next to someone with an Active Thunder. His blue F250 and trailer were pretty nice. Too bad I never saw the boat.
She didn't miss a beat. Pretty psyched right now. About a dozen or more dolphins even came by to give their blessing. She's not fast, but she gets up on plane quick for a big boat. 4,200 rpms and 35 seems to be wot. I held her at 3,800 and 30 mph most of the ride.

Glad she’s running good for ya!

Thanks Tom!
I noticed she's running a little rich when I was flushing on the muffs last night so it's time to start dialing the carb in a little better. The good thing is I burned through most of the old gas. I thought I was at a 1/4 tank when I got back last night, but it only took 54 gal. I put in 36 gal to top it off before we left. Can't really complain about that after a full day of boating. I'll have to look at my Autometer gauge set up, but I'd rather think I have less fuel than the other way around I guess.
Now to get rid of the greasy hand prints. Dawn didn't cut it. I'll try Simple Green next and then the purple stuff. Once I do that I need to get a good coat of wax on everything. I think it's been a couple years. I'm sure that's why I'm having a ***** of a time with the oil stains.