Permission + of + gerund - Is this grammatically acceptable to modern readers?

This is an odd sounding turn of phrase. I think what is happening is there are some native speakers that have a set of secondary rules for preposition selection that are basically hierarchal. This is especially common with for and of. So you have "entreated PP1". PP1 has *for the permission PP2". And PP2 has of attending and reading PP3 again. Strings of prepositional phrases don't have to be nested like this - they can just be concatenations. Some people signal the nesting by fiddling with the order of prepositions, which end up creating some odd looking phases when viewed separately, but are usually not noticed at all when spoken or read quickly. I do this to some extent, and occasionally have had to explain stuff or rewrite stuff to accommodate people who simply couldn't parse my way of assembling groups of PPs.

So even though permission for is normal, I suspect it has gotten trumped because it is an embedded preposition. The for got used up or raised to PP1, and the embedded PP2 wanted a preposition that would mark it as embedded. I haven't ever found anything written about this. I just know it exists, it varies by dialect, and can cause real confusion even among native speakers.