44 mag loads in a 44 spl?
I would say absolutely not! First of all, regardless of the gun, I believe all .44 special guns have thinner cylinder walls, therefore weaker, than .44 mags. While modern .44 specials are certainly stronger than the old ones, and the modern .44 specials can handle loads hotter that what is published in the reloading manuals for . 44 special loads, I would not consider loading ammo to be shot in a .44 special to approach .44 mag loads.
I have only one .44 special, a Ruger Blackhawk of modern manufacture. I load it about to shoot primarily 210-215 grain cast bullets at 900 FPS. This is "warmer" than what I can find published in the reloading manuals, but does not come close to .44 mag ballistics. John Taffin, one of the foremost experts on this subject has published data hotter than this, but I am very reluctant to use it.
Personally, I simply "pet" my S&W revolvers and almost never load ammo to the max for them. I consider .44 mag, factory loaded JHPs to be very warm and would never consider a load that hot in a .44 special. Why risk it?