Old 99 Take Down conversion 3030 to 3530

I have a 99 take-down in 30-30, built in 1909. The barrel is ruined by corrosion. I would like to re-bore to a 30-30 wildcat such as 35-30-30 (35-30).
The gun is in poor condition finish wise so no collector value lost. Bluing is gone on the receiver and some previous owner sanded the stock.
A possible stumbling block I see is the dovetail under the barrel for the fore stock retainer. It has a deeper slot for what looks like a retaining hex screw. I calculate with measurements that the thickness of steel remaining if the barrel is re-bored to .358" will be only 0.088". The area of this hole is only .10" sq., however.
Will this be a problem? (Considering that at.308", the steel thickness would be only 0.110". Not much thicker)
I originally was going to re-bore to 32 Special, but when I reamed the barrel out to 0.315" there was still rifling visible, although not measurable by slugging the barrel.
Any advice would be appreciated.

I am no expert on reboring, but I had a few thoughts... The retaining hole is irrelevant, I think. It is like the holes cut in an I-beam... there is no engineering loss in strength over the span. A small hole does not affect the strength of the barrel in that area, as understand. After all, when was the last time you heard of a failure because of the thin wall of a drilled hole blowing out? There have also been many historical instances of holes drilled completely through, to "relieve pressure". I think that the best course is to just find a good used barrel, even if it takes a while in the search. But, as a bit of a wildcatter myself, my second thought is to rebore and see how it performs. I mean, what can you lose, besides the barrel (and a few $)? But, I recently got a 1912 takedown (22 HP) for $395 (with a great bore), and a 1925 in 300 Savage (also a takedown, with a mirror bright bore), for $185... after I sold the scope. The receiver was drilled for the scope mount, therefore the low price. I think it would pay you to mix and match, rather than rebore. But!, When I was in college, my roommate loaded his Winchester 1400 12 gauge shotgun and fired a few rounds. One of shells was a 20 gauge, which slid forward in the barrel without ejecting. When the next 12 was fired, it knocked him on his ass and bulged the barrel just forward of the chamber... but that was all. Barrels are strong, and made with a good tolerance (even back at the turn of the century). I suppose the final answer is, who knows? I would look upon it as an experiment...

what's wrong with the 32 special? new grooves will be cut in any rebore. Sounds like you have it figured out..35 cal takes too much metal away, but the suggestion of finding a good used barrel makes more economic sense.

PS, I've been considering the same thing for a corroded Savage 30-30 barrel