LRB that is a good question! If you use the Lindsay template with the parallel heel the heel angle is set by the template. To get more lift on the graver I do a relief grind of about 15 degrees then sharpen with the template. If you use conventional point on your graver you probably can do as you said. You may be able to alter the angle of the template if you vary the surface height that the template rides on but then the angle may be hard to repeat.
That is the reason I have both the GRS duel angle sharpening fixture and the Lindsay Universal Template. If I want to make a special grind or just want to know that I can make another graver just like the one I am using I can do that with no problem, no guess work. But once I have my graver blank ground the way I want it then I can touch it up with the template.
I know that there are a lot of guys that can sharpen by hand and get good results for much less money, I am just not one of those guys. My engraving quality went up considerably when I finally spent a few bucks on my sharpening system. I do not break as many points and my cut lines look much better. If you have ever watched Hershall House videos, he uses I think a laythe tool sharpend with a huge heel and does marvelous work. Unfortunately I am not that talented.
I will second that money spent of engraving classes is money well spent, if you really want to engrave. Then it's practice, practice, practice.