The tape measure in not straight, but the Transom Assy, is basically 1 1/2" below the top of the transom cutout...

Don't get too concerned with how close the top of the transom assembly is in relation to the raised part of the transom. Your best reference point is propshaft height in relation to the running surface.
In the early 2000s we started playing with transom cutout heights. We started going as high as we possibly could on the cutouts. Our limiting factor was header clearance under the engine hatch.
The combination of raising the cutout and installing imco shorties when they first came out is what finally started getting speeds in the teens with the 500 efis.
I remember testing early imco lowers and having issues with too much water pressure

What propshaft high where you running as fastest ? Was this whit or whitout extension boxes ?

When I was there we never rigged any 30s with boxes. It has been a while but if I remember correctly the highest we ever tested the drives on a 30 was even or 1/2" below the bottom of the boat. Now this was before the 2" and 3" shorties were available. That boat was running 500 efis and ran close to 115 in the brief testing we did
I know the 36' zipp express ran 116 with 500 efi sand the props shafts were 1.5" above the bottom
I would love to rig a 36 with 525s and get the drives as high as possible. I would be interested in seeing what one could do with the shorter drives and much better props that are available

Going to try a -2 IMCO over the winter and see how that works...

Dean
I finally mounted transom assemblys . Mine are 3/8 down from top . We test fit the xr 2" short sportmaster lower. It put tip of nose exactly even with bottom. How did yours run with the 1 " and whats your hp?