I had an early blue-case LA25 on a scratch-built Goldberg Shoestring, nearly identical in size to the Magician, and it pulled that model just fine. The later silver-case version is stronger but the blue one works. Just in terms of reliability and avoiding high-castor fuels I suggest one of your modern-era OS engines, the 25 or the 32.
The "old" 25LA runs OK, but I am a bit concerned about the power available for a Magician. "New" 25LA, 25FP, 20FP if you follow the directions to the letter, OK, but old 25LA is pushing it. The only hesitation have about the 32F is that I don't have a good tested setup for it but it's plenty powerful enough.
40FP, maybe if you have one you know for sure works properly, but the typical stock example is FAR too powerful for most people to handle on this sized airplane.
Of the others (long list of low-performance 4-2 break motors), I would choose a Fox 35 but the usual caveats apply. I have done the Fox VS 20 and 25FP switch before, of course, and there's no comparison overall. The Fox might be the best overall choice between the rest of the engines, but replacing it with the 20FP felt like gravity had been turned off in terms of vertical performance.
Brett