Here are some thoughts with being able to restore the old NV if needed in the future. If you use the TT NV and do a good job of mounting it with JB Weld, it will be almost impossible to remove. OTOH, using one of Larry Driskill's NVs may require drilling, but it can be fitted using fiber washers on either side of the crankcase to manage air leaks since it's retained by a nut. If you want to later restore the original NV, you can always make a couple of bushings from brass tubing to fill in the oversized hole.

I think my preference would be to rely on mechanical attachment rather than epoxy - I like JB Weld, primarily because it is so tough.