You could also use a 3/4" fpt X 3/4" mpt bushing. Each one will raise a head approximately 1". If you need to raise it more than that, screw two together. The nice thing about these is that you only have to dig down to the fitting the head is screwed onto, rather than digging a larger hole to accomodate the flexible swing pipe.
Yeah, do it that way because it's easier. Then, when someone steps on the head, and breaks it, you will have to dig a trench five times bigger to replace the broken fitting because there isn't any 'give' in the flex joint that you don't have.
The old way of installing heads was to have the T-fitting verticle and connect it to the head with a nipple.
The two biggest problems with this, was that you had to get have a collection of nipples to get the proper height of the head to the surface of the turf or garden, and nipples aren't adjustable. Either nipples, heads, or the pipe will break when someone stemps on the head, or from the forces of the earth moving the head to the side.
Mick