Most mods are 510 threaded - just use a 510 to 808 (or 510 to KR808D-1) adapter and some 510 to 901 adapters work too. Goodprophets has cheap adapters.
And if you get a 3.7v mod it will be the same voltage as V2. (V2 is not 4.2v - that's just marketing bs. V2 like all other real 3.7v batteries is 4.2v right of the charger then drops to a 3.7v plateau and they are called 3.7v batteries). Don't get Ego (not a mod anyway but also is not 3.7v - it's 3.4v).
You can also use a variable voltage mod and crank the heat up a bit like up to 4.2 (make sure the carto is damp)
I use the following with an adapter to vape KR808D-1 cartos
Riva 510 kit from Liberty-Flights.com only (we know their kits are now all new 3.7v stock from the correct manufacturer)
3.7v box mods from ECF Buying & Seliing/Modders and Accessories
and one of these days I'll get a vv mod