The local store that I buy my supplies from has not carried 7mm-08 brass for the last 6 months. I got a little tired of waiting so I did the next best thing (sort of). Since they had a mountain of 243 brass (no 308) I bought that. Now, here is what I did. I ran them through the 7mm-08 FL sizer, trimmed them and then annealed. The question I have is in regards to neck thickness, do I have enough? What kind of brass life can I expect from these?

I sure wouldn't worry about taking 243 to 284. I've taken 284 to 338-416 and get 4-5 loading. Glad too see you annealed them.

Guys take 358 to 411 for the 400 Whelen all the time.

Good to hear, thanks!

You can use a center punch to open a 7-08 case up about .030 over size. Then use the bolt to push the expanded case into the chamber.
Pull the case out and you can measure the inside diameter of the chamber neck.
Bases on that measurement you can probably use common 7.62 Nato brass until you get a supply of the correct brass.

When necking brass up from its original diameter the neck walls will naturally be a bit thinner than they started out. This is not too much of a problem in itself, but the neck can be unevenly thin with some thin spots in the neck walls. This could result in some premature splitting of the necks after one or more firings, but by and large, you're probably fine for several firings in the 7-08 incarnation. I'd have done the same thing in your situation.

I necked up a whole bunch of .243s to 7-08s. both new and 1x. did not anneal just loaded 'em up and shot them. This was back when 7-08 was still a wildcat. I shot that brass until they standardized the 7-08 and proper brass became available. How many reloads? Don't know but it was a bunch.
Using my KISS methodology and a good Douglas barrel, my first ten shots (with no barrel break-in)using the cobbled up ammo, went into 7/8".