Pieter,

I really don't think the 525mm blades would work well on that size machine. Though they would work there isn't enough blade to load a 46 size engine.

I'm running 600mm blades on my 46 and 50 size machines and have more power than I can use. You'll have to run a much higher pitch and/or lower throttle to keep the rpms down in a reasonable range.

I'd really try to see if you could exchange the blades if you can.