Your electrician buddy was close to having it right- the old timer term for a split bolt was a "Burndy", not gurney.
Burndy was an original producer of the split bolt connector, and was the only brand available in most places, so they were simply referred to in the trades as Burndy's.
Kind of like channel locks and vice grips.
And yes, you can get correct connectors for AL to CU. You can also minimize oxidation with a product like Penetrox brand anti oxidant (also made by Burndy).
A quick tip: once you have tightened the split bolt, hold the nut part in free air with channel locks and smack the top of the bolt with a hammer a few times. You will get at least another half turn on the nut afterward.
If you make oxygen free splices, you probably can forego the Penetrox. You should have on hand at least a couple types of splicing tape to make a correct connection. Split bolts have many sharp edges that will cut right through regular scotch 33 or 88 vinyl. A healthy ball made with Scotch 23 rubber splicing tape or 130C linerless splicing tape, followed by several tightly wound half laps of 33 or 88 will minimize the chance for premature failure. Be sure to fill all the voids in the connector. And if the splice points are subject to vibration, a couple wraps of friction tape will further lessen failures.
The fact is that making low resistance, low oxidation rate, highly reliable connections in feeder size cables is usually better left to a professional.
I will not speak to your reasons for splicing as I do not know the entire scope of your project. I would, however, hope that you would carefully think about your project and take safety seriously if you plan to back feed your home electrical system. I might be the guy on the other end of the pole repairing your incoming line after the storm.