I am only 65 - so my opinions may be attributed to youthful ignorance--
Over the years,I have seen/run the older magneto engines -different sizes G38 etc - 45/62 etc..
Unless you are simply a nostalgia buff- this type of engine - or any of the older converted chainsaw stuff - is really at a power /smoothness disadvantage to contemporary designs.
Example:the 60 ZDZ single will outpull the G62 - on Big props - 24x10 Menz Std at a min of 6000 and up to 6500 on good exhaust - plus much lighter and way smoother.
Also The same engine beats the G80 twin- same props -
The New 3W 50 is another example - very smooth - and tho not as powerful as the ZDZ60 - is simply excellent .
Both engines also have a rear carb - which allows for nice smooth cowlings -on planes such as a P51--
If you are buying a new engine -you should consider this approach-
There IS a big difference.
Also the prices are close to the older types.
If you are a nostalgia buff - that's a different story.