Griff: The porpoise does seem less with a little chop. That rpm situation is what is most confusing to me also, but I guess the more slip % is letting the r's go higher?

Michigan troll: I have a BBC 489ci, carb, w/ a retro roller setup making around 500hp. Did that setup make a rooster tail?

Sounds like your over trimming the 28 or it has been cut down quite a bit.
Ours throws a big tail from 8 foot full out to about 12 foot at 3/4 throttle. I trim +3 of neutral maybe a little more for full out. But our is a drivers boat. You play with trim and tabs at all speeds to keep it level. They need 1 foot of chop or more for full speed and less tab.
When I purchased the boat it had a 28 Bravo. I pulled the spacer and I had a hard time getting on plane and could not run over 65 without blowing out the prop. The 28 Max fixed everything and now will have it tuned and labbed.

Prop is 15" dia. Im only trimmed maybe +3 from N also. I have it trimmed for max speed and with the porpoise, it is loose!

Michigan troll, what power do you have?

Ours dynoed 814hp @5500 and 810T @4700. Currently running a stock 28 Maxximus. You should be able to turn a 24-26 Max.