225 slant rebuild for more power

You got lucky. Don't steer him in a possible wrong direction here. There have been LOTS of problems regarding this. This article is just the tip of the iceberg.

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To the OP, run what you want, but you'll not see me run an HV pump in a slant.

I agree AND the 225 is a low rpm engine anyway. (4-1/8 stroke) 4500-5000 and you're done.
There is s lot of info on slantsix.org sbout this.