Simply drill a 13/16" hole and install! It is really that easy. The great thing about using bulkheads, is there is no need to passivate the conical.
When holes are plasma cut out of conicals, sparks are produced of dissassociated metals which usually cause the inside of the conical to rust unless special procedures are used to passivate the stainless. When fittings are TIG welded onto the hopper, they must be fully electropolished to avoid rusting because of the heat affected zone (HAZ).
On top of all this, many companies that make conical fermentors for homebrewer's talk up a storm about "sanitary welding". That is fine, but when you are sanitary welding a THREADED fitting into a FERMENTOR, then nothing is really sanitary!!! You can not effectively sanitize a threaded fitting unless you boil it, which is only possible with a removable bulkhead fitting.
We say - why bother with all of that mess? when you can do it for less!!! Both methods work fine (welding vs bulkheads), but bulkheads have the advantage of being MUCH cheaper and more versatile then welding on fittings, and are just easier to sanitize.
If you do decide to purchase a pre-made conical - insist that the fittings be triclover ferrules and clamps. If there is a ball valve being used, it must be removable for boiling. Ball valves can carry media behind the ball which is why it is so important to be able to either boil the ball valve or run boiling water through the ball valve to sanitize.
The reason we use stainless valves during the fermentation process is that stainless is inert and will not interact with fermented wort. Generally, brass and copper are perfectly fine to use during the wort production phase, but not during fermentation.
Fermentor bulkhead/ball valves include DUAL High temperature fda gaskets (one for each side of the conical). While it has been proven that only one gasket is necessary, we like the idea of adding an extra layer of insurance by sandwiching the conical between 2 gaskets, we guarantee a leak free connection!!!
