While I like both 45s and have 3 N frames that are cut to take both rounds, I would prefer an L frame in straight 45 ACP. The reason is I would want it for a carry self defense gun and while the 45LC is a great round it does have a draw back. The rim is very small. The 45 Colt has about the same rim diameter as a 44mag ( actually .002 smaller). It only protrudes from the case wall .016. This can cause it to slip out of the extractor on occasion when the extractor is very far out. If you were to camber the cylinder for quick reloads, which is a major plus for the 45ACP and clips it would make extraction of 45 colts even more likely to slip out of the extractor. If you SD carried it with ACPs and just used Colts occasional it would be OK, but, I believe in a short barreled L frame the advantage of 45 colt over ACP would be small anyway.
While the cylinder of the L frame will take reaming to 45 cal cartridges the barrel threads are of a size that would leave a very thin forcing cone. You can't increase the tread size because then the web underneath between barrel and yoke would be paper thin. But, then Taurus has done 45 ACP with the same frame size so it must work.