You state that the compression is "low" on cylinder #1 (flywheel end). What are the numbers for your compression test? Also did you do a dry test then a wet test? Do you also know what the numbers were before experiencing the loss of performance? NOTE when doing a compression test all 4 plugs should be removed, the choke OFF and the throttle set to full for accurate numbers.
Does the engine run as smooth as it did before or does it seem to be missing a bit? Do double check that the plug wires are in "order" a common mistake.
As per Joe's question, did the prop cleaning get your RPM's back after cleaning? A dirty prop can really reduce performance as can a loss of a cylinder with no compression.
How long since the engine had a tune including timing and a check of the centrifugal advance function?
Dave Neptune