Most any smith with a lathe can turn a Krieger so you can install it yourself, no issues there.
As for a "cheap Savage Donor Rifle", you can grab a new Stevens for $300 most anywhere. The Stevens is a pre-accutriggern Savage, though they are now center-feed. I feel that other than the Savage Precision Target Action, they are the best starting point for a semi custom build, as you're not paying extra money for a bunch of parts you will be removing, like the trigger and stock. I built my .222, which is capable of .25MOA or better accuracy, for right around $1200 complete, minus scope.
Here is a list of what I bought:
Action, Stevens (used):.......$200 (new:$300)
Stock, SSS Dog Tracker:......$325
Barrel, Pac-Nor:...................$400
Trigger, RB SAV-2................$150
SSS Recoil lug:....................$30
Scope base, Bench Source:...$75
Burris Rings:........................$50
single shot ramp:.................$18
As for the better Savage triggers, one of the better models you can install yourself is the Rifle Basix SAV-2, which is adjustable from 4oz to 3lbs. I have two of them now, one replaced the Timney that was on my .222 and the other is on my deer/varmint .243. The .222 is set to 5oz and is quite crisp, definitely better than any accu-trigger I have felt. The other is set at 24oz, still good and crisp as well. I have the Timney on my .308 Stevens now, and it is set to 2lbs and is a nice trigger as well.
Though the best Savage trigger you can buy is made by Sharp Shooter Supply and is the Evolution Trigger, though you need to send them your action to have it installed. It's about as close to a Jewell as you can get on a Savage. I have tried one in the past, and it was honestly one of the best feeling triggers I have ever used. It's a 3-lever design and is definitely worth the money to have it installed.
Sharp Shooter Supply also makes a trigger you can install yourself as well, and it is adjustable from 12oz to 2lbs.
Jim Briggs from Northland Shooter Supply is a great guy to talk to, as he stocks many Savage rifles, actions, barreled actions, take-off stocks, barrels and other parts, as well as new barrels from Shilen, Criterion (Krieger's button rifling division) and McGowen. He is a great guy to deal with as well.
Kenny