Unfortunately, those dimensions do not EXACTLY match any wildcats that I know of, but being wildcats, they seldom do. Every wildcat shooter who has a chamber reamer ground will use his own dimensions and even the reamer grinders themselves will often vary some of the dimensions as they see necessary.
Your cartridge is very close to the 6mm Walker International Long and since there were several variations of that cartridge I’d say that is what it is.
The 6mm Walker was developed by Mike Walker of Remington by necking down the 250 Savage and pushing the shoulder back to reduce case capacity slightly. The Long version is more recent and was made simply to get back a little of the case capacity. The original version was a short range cartridge and the Long version is, as you’d guess, a long range version.
The cartridge was very popular in it’s day but has been replaced by similar sized 6mm cases with more efficient shoulder angles such as the 6 HLS Hunter and in the last year by two cartridges from Scandinavia, the 6 x 47 Swiss Match and the 6.5 x 47 LAPUA. The brass for those two is of such high quality that wildcatting the 243W, 308W, and 250 Savage brass is a thing of the past.
That’s today’s lesson in wildcat cartridges. ;) ;