I have a 29 scarab twin 350's. At wot i'm 5-5050 rpm's and according to speedo (non gps)69-72. Since i'm told peak power is 4850rpms i'm assuming my best bet now is to try to drop rpms 1-200, keep max speed, and maybe try to increase mid range. I'm turning 23p mirage plus's (3 blades)...Any suggestions ?

25p Mirage plus's. 22 or 24 Bravos will increase your cruise speed but may or may not decrease top end

Labbed 25's. The stock 25 Mirage Plus's should drop you 3-400 rpms, labbing will get you 200 or so back which will put you at your 4850 goal.
BTW, are these 350 Mags? If so, then I think you're right where you want to be rpm wise.
I'd contact one the prop co's. that advertise here for advice as there are several things to consider when reproping.

You could try a pair of older Mirage 25's if you can locate them. Not the Plus. The old style 25s have less cup than the newer "Plus" Mirages.

I run a labbed 25 Plus. I gained about 2.5 mph after having the 25P labbed. My spare prop is the older style 25 {not Plus} and performance is very similar.

BTW, Throttle Up labbed the prop for me and they dis a great job.