We've never had Chevies, but I can tell you that at the sales barn, those little things bring a lot less per pound than other breeds.  Get either Dorsets or Polypays, or a mix of the two.  If looking for replacements, breed them back the same and pull the replacements out of those foundation ewes.  For a terminal cross, breed them back Hampshire (If you can find a Hamp that hasn't been contaminated with Suffolk crosses).

After 13 years in the sheep business, I can assure you that a white faced ewe bred Hamp will produce a wonderful lamb.  One that will gain and one that will bring top dollar when you sell him as a 130 lb fat lamb.

Start small, with young ewes and build, but be careful what and where you buy.  The learning curve in sheep is high.

And, I am dead serious on this.  If your wife isn't involved, you will have a massive struggle on your hands.  The best sheep operations I have ever seen, including our own,  ARE MANAGED BY WOMEN.  They don't have to do it all, or any of the hard stuff for that matter, but let them sweat the small stuff, females just are better, and I know a lot of shepherds that agree with me.