Re: add soffit Vents to an Old House
My roof survived with no venting for 86 years, appears to have the original roof deck and shingle life wasn't an issue when they had asbestos in them. I love seeing 60+ year old roofs still in service, but you're lucky to get 20 out of the new stuff.
But old houses were designed that way. Attic venting is a relatively newer (last 60 years) concept. Then again, so is insulation.
For round vents you can use a hole saw. You can cut through wood pretty fast with a hole saw. Easier than a reciprocating saw for square holes I think.
But as mentioned, you'll need a LOT of them.
1925 Two-Story Stucco Beaux Arts Neoclassical