The only stainless receivers I know of are Volquartsen and Tactical Innovations. Cost for Volquartsen is around $450 and TI isn't far behind.
I'd suggest buying the Kidd aluminum receiver. A silver (clear anodized aluminum) Kidd receiver is around $220 and comes with a picatinny rail. This would be the slip-fit model.
Better yet, just spec. out and buy a complete Kidd supergrade barreled receiver with bolt, trigger, etc. The fit, finish, and accuracy from Kidd is virtually impossible to beat in a 10/22-platformed rifle.
I too went down the road of upgrading my Ruger receiver with a barrel (Volquartsen), then a firing pin and extractor (Volquartsen), then an entire bolt (Kidd), then a trigger group (Kidd), then a stock (Revolution). Then I bedded it and installed a pillar, etc. At the end of the day, I could have spent less money (and certainly less time) and would have had a better performing rifle if I had just bought a complete Kidd from the beginning.
The nice thing about the Kidd Supergrade is you can easily swap barrels. This allows you to buy one complete rifle...then you can buy additional barrels for whatever purpose you might have. Barrels are only around $200, so you could have a lightweight hunting barrel and a heavy bench rest barrel, for example.