no that all looks perfect, i usually shoot for a little bit less than 50% bore and a 7 degree taper divergence but thats using a cnc lathe so i can actually interpolate the curve of the piston.
i actually had to quit making these because we couldn't find good aftermarket heads to machine, the decomp holes were too sloppy and kept breaking through to the bore, but you can see from the profile its real close to yours.
when i used to be able to get real french MBK heads these things were really really nice. I have been thinking about going back and redesigning it for 45mm because it would be that much farther from the decomp and might work, but i have a lot of other irons in the fire.