While Dirt did a good job of making a budget Vortec combo work well, his grinding of the retainers is not soemthing I would even suggest...
I would rather see a person take a hand grinder to the top of the guide boss on the head, then chamfer it with a reamer, than do that.
There is no reason to grind on a component as critical as a valve spring retainer when you can do it correctly (and more easily, repeatably) with a $45 tool.
If you alter the temper of the retainer, cause a stress riser, go too far and the keepers come through the bottom, anything.. It just cost you a motor over a $45 investment that you can re-use over and over again.
I've done at least 10 sets of heads with my cutter. That works out to $4.50 a set so far...
I would buy it and then re-sell it for half the cost than take the risk of grinding a retainer.
It is like looking down the wrong end of a loaded gun..
Of course there are always those that say, well it worked for him. Good deal..
I'm one tightwad sucker and in that scenario I'd be dishing out the cash one way or the other to have the HEADS machined.