Looking at replacing wet cells with agms. The agm's use a m8 bolt, can you convert to sae. Here is a link for that type of connector.
Solid Brass M8 to Standard SAE Post Battery Terminal Adapters | Remy Battery (https://remybattery.com/brass-m8-to-standard-sae-post-battery-adapter-tp08.html?srsltid=AfmBOopR06fDYGVl9ddodMGoiBWJMh0b4Zy-fIIvEBCLWjHGBMMelrvK)
Don't see why that adapter wouldn't work, but is it really necessary? What brand of battery are you considering?
Most battery manufacturers offer their batteries with different style terminals. Is the same size AGM battery not available with post style terminals?
It is a Renogy, which I found on amazon for 379 each.