G'day from Down Under, Jimmy...
I own four V70 handhelds and one V75 handheld and the good news is that the Earthworks WL40V capsule is compatible with both.
The not so good news is that it's pretty much the most expensive capsule out there, costing around $800 USD or roughly £650 GBP.
It's also worth noting that best results will be obtained from it after upgrading older V70 firmware to the latest version via Line 6 Monkey, which will require both a little time online and hooking up to a V75 receiver.
Indeed, keeping my initial inventory of four V70 handhelds, eight V70 beltpacks and eight V70 receivers "up to date" heavily influenced my subsequent purchase of a "stand alone" V75 handheld "kit".
So, much to the undoubted annoyance of various sales teams, I'd heartily recommend sticking with your existing N/D767 modelled arrangement, …even more so if you don't have the opportunity to "try before you buy".
Incidentally, given that our handhelds effectively "duplicate" a "cabled" connection, (and that very few outlets seem to stock the WL40V capsules) the easiest way to effect a "trial" (albeit somewhat limited) might be the demonstration of an Earthworks SR40V cabled handheld at a stockist near you, such as KMR Audio: