Colt Ace floating chamber .22 kits have gone out of sight like everything Colt (see American Rifleman on Colt `snake’ revolvers). FWIW I bought a Remington WWII M1911A1 in 1975 for $125.
I recently bought for a reasonable price a Colt Ace II .22 conversion kit; haven’t fired it yet. Much simpler design with an alloy slide & one piece barrel. Comes with a mainspring housing & spring but I can’t tell the difference with the original.
As for Garands, I bought a new receiver in 1998 & one of those all but receiver kits. Put it all together & it shoots fine.
Oh, I know, those original Colt .45/.22 conversion units are over $400 used at the gun shows here, when you luck into seeing one. Everything’s priced WAY out of sight. If I had every gun and such I owned and sold it at today’s prices, I’d have a pile of cash to die for. But I got to enjoy owning and shooting all that iron, so it’s cool. Can’t buy memories, sure wish we’d had Youtube for showing off our shooting skills and such when were younger... :)