Although I see nothing "wrong" with using the Speer data, you might drop to 5.4 grains to start, see how accuracy and functioning are, and go from there. Since the Precision Delta bullet is not the actual bullet tested with the Speer data, it would not hurt to start a smidge lower. Not exactly sure of how exactly the ogive of the PD RN matches to typical "GI style" 230 RN FMJ like WW or Remington, but if very close, the 1.26" OAL seems reasonable. Had it been a TC or HP style, 1.20" would be closer to ideal in my experience, but again, all guns are a rule unto themselves. My GI spec 1911 will not chamber 230 Gold Dots seated to 1.20", that my long leade P220 does with ease.
If you get the chance, you might try to find a copy of the now out of print MidwaUSA's LoadMAP for .45 ACP. This is an incredible piece of work, and they really did some extreme testing of nearly every bullet available at the time (1998 or so). The MAP stands for Maximum Average Pressure, and that is exactly what they did in great detail using modern equipment, giving pressure results per charge weight. FWIW, Every 230 grain FMJ RN they used, has a max charge a few 1/10's above 6.0 grains (some as high as 6.5 grains of WW231), and still did not exceed the SAAMI 21k psi max allowed chamber pressure for std pressure .45 auto.
My friend and fellow THR member MAXM, writes for the Italian version of Handloader magazine, and has a fully equipped CIP ballistics lab at his disposal to verify data. He wrote an incredibly in depth analysis and testing of WW231/HP38 concerning .45 Auto ammo, and his results were very much in line with the Midway loadMAP data. Bottom line for me; any well assembled ammo using the bullets you mention and worked up max Speer data would be safe in any soundly made/maintained .45 Auto pistol. How accurate they are, well that's another story, and only until bullets meet paper will you know.
