Use the '65, the Model 28 is too heavy and will slow you down. Also get some comp III speed loaders.
I do quite a bit of pistol competition using at revolver. I found my Model 64 is accurate enough and much faster then my Model 28.
Nothing against the 28, I love mine, I was issued it when I hired out in LE and was allowed to keep it when I retired. Its a better all around revolver but I'm much faster with my Model 64.
The exception is Bowling pins. Speed, as far as getting it out of the holster isn't that critical here, but the heavier weight makes keeping it on target easier with the heavy 357 rounds I use on pins.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071