Neat idea. My same load feeds a '73 and '92 lever gun, so not really an option for me.I've gone as far as getting solid base wadcutter bullet moulds for 44 and 45 caliber bullets. Fun shooting at the range for a day of plinking.
The downside is that once you handle an N-frame with that slim .45 barrel you'll sell everything else.
Is the conversion bored out or does it need a donor barrel and cylinder?
Cylinders are typically rechambered, which is preferable anyway. A custom gunsmith will cut a better chamber than a manufacturer. Barrels are trickier. It used to be no big deal to send a barrel to Cliff Labounty for reboring for $150-$200. Since his shop is no longer in operation, it's a little trickier to get it done and a replacement is often easier. Which S&W makes a good barrel.
On my converted Model 28-2, I installed a factory ACP cylinder and sent the barrel out to be bored and rifled by a now deceased gunsmith. As CraigC mentioned, smiths that are willing to bore and rifle a revolver barrel are getting hard to find. And 45 caliber factory barrels are not easily scrounged either.
Seems to me that trigger is from Bisley,
Correct. I put a Bisley trigger in it and an aluminum grip frame which I reduced the flare on.
Does your 624 have longer bolt notches like on this picture:
