It would "probably" increase accuracy to some extent but NO guarantees.
The Python barrel has a faster rate of rifling that increases accuracy, and Colt always made their own barrels. Colt barrel were made to a very high standard and were famous in the industry for quality and accuracy.
In addition, the Python barrel was tapered toward the muzzle to grip the bullet better as it passed down the bore.
The limiting factor is that the Ruger, while a nice gun, may not be itself accurate enough to take advantage of the better quality and accuracy Colt Python barrel.
So, you might see some increase in accuracy, but the Ruger would not be the best choice if you're looking for a pure accuracy custom job.
For that, you'd be better to use a selected S&W revolver which can make better use of the better Python barrel than a Ruger can.
For a pure accuracy revolver, you'd probably be saving money over any custom re-barrel job by just buying a Python or looking for one of the Dan Wesson's made when between bankruptcy quality was good.