Thanks bajaman. I no longer have the 19 to test with as it was from the loaner program. I am going to run today and test the 21 and 17 props. I thought I had a 23 but it’s a 21. I agree something is off. Maybe wrong cam like you say. I’ve been looking into some EMI manifolds since someone tilde me about reversion with a cam like this. I’ll report back with numbers from both test today. I’m not 100% sure I was at a perfect plane last time. I grew up on boats but this is the first I’ve owned myself. I think I had the drive all the way down last time but now know that would have resulted in a negative angle. Or at least I think lol. I’ll play with the trim today to see if I can find the sweet spot.

Yeah...you'll get there...just will take some time. Next time out just keep trimming up (once on plane and running 25 + mph) until the prop blows out, i.e. you lose forward momentum and the revs climb quickly, then nudge it JUSSSST a bit back down.
I forgot to ask if your boats has trim tabs? Trim tabs and drive trim can work hand-and-glove together to optimize running angle.

I do not have tabs. Would like them though lol. I have a ss props now so I don’t think they will blow out. Pretty sure I was flattening the aluminum one. I can take the aluminum one and test that too. Think that is a good idea?

Oh, if you over trim you will blow the prop out, meaning break the surface/cavitate. An aluminum prop is not THAT bad, really...not for ultra-high performance, no...but will get most of us 'runabout guys' along just fine...as long as the hub isn't spun. The last thing you need is another variable to mess with you, lol!
That 21" may be just a bit too much with your 1.32:1 ratio. Then again, a strong 454 should be able to twist that thing pretty well.

Ok back from testing. Well testing one prop. Had some other issues with fuel today so I need to sort that out. Anyways I had the 17p Mirage plus mounted up so ran that first. Did like you said and got the boat up to about 25-28 then played with the trim. I could feel it ease up and hear the change in the motor so I think I had it on plane correctly. Then I eased into wot. Managed to get 49-50mph at 4500rpm. Might of had a little left but ran out of smooth water and had to turn. Was able to achieve those numbers twice with the 17p. My issues with fuel started after I changed to the 21p so I never got to run that again to get new numbers. According to BBlades prop slip calculator I’m at 8.89% slip so that is closer to what it should be?

Sounds like you are right there or damned close! I think that 17p is what is going to do it for you. I agree with your slip numbers:

https://cimg3.ibsrv.net/gimg/www.off...39aa2b8ddd.jpg

Man I sure hope so. Thanks for all of your help!! Now I need to find out why it dies in reverse and what the backfire is all about. Engine was pulled late last year. Maybe the cables need adjusted on the shift linkage.

Dying when shifting to reverse IS often just a case of cable adjustment...as for the backfire, that of course isn't normal and can be dangerous. I know NOTHING about that Quick Fuel carb but there could be an issue with it or in the timing.

I have a complete Bennet setup that I will sell for $250 shipped. The tabs are 8" x 12"