The following is basic mechanical detailing reputable smiths recommend. Most likely, a Ruger 45 will need all of these:
1) Action Job
2) Free-wheel cylinder
3) Remove Endshake (if needed)
4) Set Barrel/Cylinder Gap to Minimum
5) Oversize locking basepin
6) Open cylinder throats
7) Recut forcing cone (if needed)

Recrown muzzle (if needed)
9) Bowen Target Rear
10) Custom Front (modified ramp or post)
11) Ejector Rod housing key (keeps housing from coming loose)
12) Set timing & headspace (as needed)
Using a reputable smith such as David Clements, Alan Harton or John Gallegar will cost around $700 - $850 for this work (including shipping). Personally, if I had $1200 to spend on another custom Ruger, I would have the smith find a 44 SBH cylinder and linebore & rechamber it for 45 Colt and do the above mentioned work (minus the cylinder work). Octogon barrels do look slick, but I wouldn't buy a custom Ruger that had cosmetic bells and whistles that lacked the basic mechanical detailing & accuracy tuning described above.