Limiting the bullet weight to 240 grains certainly maximizes the number of variants that could be considered "best". I would guess that the variants that are most likely to produce excellent accuracy with cast lead bullets would be the 29-5 and 29-6. These are pre-lock (29-7) and have cylinder throats standardized at 0.429", although some 29-5's may have been made with cylinders that had the 0.432" throats. Model 29-4 and earlier versions of the 29 had a cylinder throat standard of 0.432", which is fine with jacketed bullets, but accuracy with lead bullets sized to 0.430" may not be great.
For the pre-endurance package Model 29's, a limited amount of full power magnum loads and shooting mostly 44 Special or loading your own reduced power loads will provide you with a life time of use. I think most Model 29/629 owners find that full power magnum ammo is not very pleasant to shoot.