FWIW, I replaced the issue-style hammer last Summer with a Caspian Arms rowel Commander-style hammer (only) on my Remington Gov't Model 1911R1. ($30, IIRC)
The CA hammer dropped right in, but the slide wouldn't cycle during hand testing - it was limited by the hammer limiting on the top of the hump of the issue grip safety.
I removed the grip safety, ground the offending hump "off" with a slight radius, cold blued & re-installed everything.
No other mods or adjustments, through about 1500 rounds so far, with an excellent trigger pull (on MY gun). YMMV.
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