I usually reload standard loads like the 230gr RN .45acp and I have factory loads to refer to (especially for COL, as you know these chamber well). This is a good reference (never have to many references when loading) along with the load books.
I prefer 1.250. Many manuals list 1.275 as the max. This is misleading as some guns won't chamber rounds this long. If you do go over 1.250, don't load a lot until you check one with the barrel out of the gun. The case should not extend past the barrel hood.
You'll find variations in profile and bullet length between manufacturers (probably among a single box of one mfr/s bullets, for that matter). When the Speer manual says 230 FMJ-RN, it's usually referring to their FMJ-RN and it will even list their part #. Same with Hornady. A Lyman manual may specify which manufacturers bullet they are using (normally the cast bullets are listed by mold #). The data included with Lee die sets may just say 230gr FMJ RN, so who knows.
Figure the COL listed in your source as a minimum and err on the longer COL side. As mentioned above, test chamber a few rounds at longer dimensions and seat about .010" deeper than where the bullet doesn't interfere with the throat or rifling when chambered. With your pistol you can remove the barrel and do the drop-in test. Once determined for this specific bullet, measure and record the COL for future reference.
If you come up with an ideal COL less than 1.200" or greater than 1.270", I'd re-check your work.
Unfortunately, you'll acquire bullets at some point that are not specifically listed in any load manual. You'll have to use a little fudging here comparing bullet lengths, weights etc with known loads and work up loads accordingly. Ultimately, you'll want a load that fits the magazine, feeds and functions in your handgun.