A20 rebuild

The other day i was adding oil and i notced a small amount of blowby through the oil cap. I did a compression test and had great compression in all cylinders (around 170 psi) except for #3 (only 25 psi). So long story short, im doing a full rebuild. My question is, is it worth the extra money to do a mild camshaft regrind and a weber carberator or should i do a stock rebuild to save cash? If any of you have experience please let me know how much of power difference ill see. Also, how much will it affect my mileage. Any advice and pros/cons help. Thanks in advance

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