I spoke with Zephyr engines in Florida a while back and got a price of $23k (from memory) for a rebuild if I could supply a good core. At the time, I was looking at a 1700 hour engines out of a Comanche that was available locally for ~$9500. So that would have put the entire package at ~$33k for a 0 SMOH engine. BUT, it would have had a 50 year old crank, a 50 year old case, etc.
Could you get a good core for less than $9500? Maybe, but you're still going to end up with $30k or thereabouts in an engine with a lot of calendar time on it.
I've looked at the numbers and figure I could take that $9500 core and put another $10-15k in it in parts and machine work and rebuild it myself, reducing the cost to $20-25k, but with no warranty support.
Ultimately, from a pilot/owner's perspective, you won't see a difference between a rebuild and a new engine. The performance should be the same. But, on the resale market, the market is efficient, and will value the airplanes differently - probably by the approximate difference in engine cost.
So, ultimately, it is up to you. All of the options work.