I'm not sure what you mean by wanting a gun "this way". If you mean with a 3.5 inch barrel, I would consider shortening the one you have if it is right for the throats.
My suggestion is to measure the barrel as is and if it's something over 452 and not larger than cylinder throats, run with it, probably after lapping, if accuracy is a concern with you. If precision accuracy isn't a concern, but the guns use will be close range only, lapping wouldn't be necessary.
If you mead that you want a special barrel installed, you don't need be concerned about a 452 barrel, or even a 451 barrel, sizing your bullets down too much for a close range gun. That's only .003 for the gun to size, which is minimal. Many commercial cherry cut molds run much more than that oversize, often up to .006, and customers have been content with their performance for years. If you start with an LBT mold, which will produce better balanced bullets than any cherry cut mold, you won't have any accuracy problems. Nor will you find a measurable increase in pressure with oversized bullets.
Since you are going for a custom gun, I strongly suggest that you have the cylinder gap set at .002 close as the smith can hold, and cut the forcing cone small and short. Most revolvers today have huge force cones which are detrimental to accuracy. Also, if the cylinder gap gets large the noise heard by the shooter is deafening, espcially if the gap is over .004. (I have measured many at .010!, which gives a report like a bomb, even with a 22 lr chambering.)
